VOLKSWAGEN GOLF 1998 (01) PDF Document

This information is intended to help you form an opinion as unequivocally and accurately as possible in the event of tyre damage and related complaints. In this chapter, you will learn a great deal about tyres and also about wheels and rims.

Tyres are hi-tech products that are optimally adapted to the operating conditions of modern vehicles. As with all highly developed technical products, tyres require proper care, maintenance and service. This is essential to ensure safety, performance and comfort for the entire service life of the tyre.

Tyres are constantly being further developed. Quality tyres are the result of modern design methods and production processes, as well as continuous quality checks. All tyres that are recommended by VW have been tested by the technical development department and have been designed specifically for each model in collaboration with the tyre manufacturers.

We therefore recommend fitting only the recommended tyre makes when renewing tyres.

Vehicle safety has the top priority. With regard to the various operating conditions such as:

• differing speed ranges,
• winter and summer use and
• wet and dry roads,

the optimal compromise for vehicle safety must be found.

Every tyre is subjected to a wide range of different driving conditions over its entire service life. It is therefore important that the basic requirements for ensuring optimal tyre performance are met.

Proper adjustment of the axle geometry during wheel alignment is an important prerequisite for ensuring the optimum service life of the tyre. Therefore, wheel alignment must always be within the specified tolerance range.

Information for wheel alignment can be found in the running gear, axles, steering section, Rep. gr. 44.

Note: Tyre damage and related problems can have various causes. It is therefore very important to ascertain whether the problem has been caused by the tyre or other components.

Normal wear and tear on a tyre will alter its characteristics. Tyre noise and vibration could then be the result. These are indications of wear and do not constitute damage in the sense of a tyre defect. Measures can be taken to at least partly eliminate the symptoms. However, in some cases it may not be possible to eliminate tyre noise completely.

The manufacturer is issued with a general operating permit (GTA in accordance with § 20 StVZO (German road traffic and licensing regulations) and EU operating permit) for the overall vehicle with all parts for specific conversions.

Conversions of wheels and tyres can only be carried out under certain conditions. When doing this, the following points must be observed:

• If the size of wheel and tyre, with an indication of the load index and the speed symbol, is included in the vehicle GTA and EU operating permit/type approval (see page 7), this wheel and tyre combination can be fitted on the vehicle without any problem.

It is not necessary for the wheel and tyre combination specified in the registration certificate part I (certificate of registration) to be fitted. All combinations approved in the vehicle GTA or EU operating permit/type approval (see page 7) may be fitted to the vehicle.

• For the conversions recommended by VOLKSWAGEN AG (see attachment for parts certificate) there are no general operating permits in accordance with § 22 StVZO (German road traffic and licensing regulations).
• Unless the wheels and/or tyres are included in the relevant vehicle GTA or EU operating permit/type approval, the vehicle will no longer meet the requirements of the road traffic regulations if converted.

These versions are based on the conditions valid in the European Union and no guarantee can be provided for their completeness. In some cases there are different legislative requirements outside the European Union.

The table included in the attached parts certificate shows the VOLKSWAGEN AG recommended and TÜV NORD Mobilität GmbH & Co. KG tested wheel and tyre combinations on VW vehicles and also the conditions to be observed for fitting. The use of genuine disc-type wheels on a vehicle to which they have not been allocated is not permissible.

The list of possible conversions deals with combinations that meet the requirements of VOLKSWAGEN AG with regards to road handling and road safety. They are the result of practical trials and are therefore recommended by VOLKSWAGEN AG.

Refer also to the new vehicle registration documents that were issued from 01.10.2005 (see page 6).

2.2 Technical conditions for converting wheel and tyre combinations

• The wheel and tyre combinations and conversions listed in the tables of the individual vehicles refer exclusively to Volkswagen genuine disc-type wheels.
• Approval of wheel and tyre combinations or a change to wheels from the accessories trade is not possible with the parts certificate attached here.
• Tubeless radial tyres may only be fitted to rims with a safety hump feature on the shoulder.
• Tyres with run-flat properties (reinforced side walls) may only be used on disc-type wheels with an extended hump and on vehicles with a tyre pressure monitoring system (see page 55).
• If the wheel and tyre combinations listed are used, the associated tyre inflation pressures must be adhered to. The tyre inflation pressures for summer tyres can be found on the sticker on the inside of the tank flap or in the tables of the individual vehicles.
• Sufficient clearance to the wheels and tyres at parts of the wheel housing, suspension and braking system is assured if the notes and specifications established in the parts certificate are observed in all operating conditions.
• Unless otherwise stated, snow chains may only be fitted to the drive wheels. On all-wheel drive vehicles, however, only the front wheels may be fitted with snow chains with the exception of the Touareg (rear wheels may also be fitted with snow chains).

For technical reasons some vehicles require wheel housing extensions (flaps) on the wing or bumper -arrows- when using certain wheel and tyre combinations.

Please check if there is a requirement to remove the flaps.

The information is located in the overview table for the respective vehicle.

Tyres of the “80” series (e.g. 145/80 R 13 74 S) will replace the “82” series (e.g. 145/82 R 13 74 S). Lawmakers have stipulated that “82” series tyres may be replaced by “80” series tyres without having been entered in the vehicle documents.

The condition for this is that the “80” series tyres have the same width, be of the same type – cross-ply or radial belted – and have the same or higher load index.

If only “80” series tyres are entered in the vehicle documents, “82” series tyres may only be used if an entry has been made in the vehicle documents.

The Plus running gear differs from the basic running gear in the following components:

• Suspension link
• Swivel joint
• Wheel bearing housing
• Anti-roll bar with coupling rod (not on Passat)
• Drive shaft
• Wheel hub
• Brake disc
• Brake caliper
• Wheel

One of the identifying features of the Plus running gear is the connection between the swivel joint and the wheel bearing housing.

A – Connection between swivel joint and wheel bearing housing on basic running gear

B – Connection between swivel joint and wheel bearing housing on Plus running gear

The 5 wheel bolts on each wheel are the most visible identifying feature. The Passat VR6 to 09.93 is an exception. From 06.91, this vehicle was produced with 5 wheel bolts, but was gradually equipped with the Plus running gear from 02.92.

The 5 wheel bolts on each wheel are the most visible identifying feature. The Passat VR6 to 09.93 is an exception. From 06.91, this vehicle was produced with 5 wheel bolts, but was gradually equipped with the Plus running gear from 02.92.

Here is an overview of vehicles with Plus running gear:

The implementation of EU Directive 1999/37/EU “Registration Documents for Vehicles” in national law and legal data protection requirements have necessitated the introduction of new, falsification-proof registration documents.

Since 01.10.2005, only the new documents are issued by the registration authorities in the event of new registrations, change of ownership, registration of technical modifications and all other matters.

The new registration documents are comprised of:

• Registration certificate part I, which replaces the certificate of registration and
• Registration certificate part II, which replaces the vehicle log book.

Registration certificate part I (certificate of registration)

• Contains all vehicle technical data which must be available to register a vehicle in Europe; however, only one wheel/tyre combination approved as standard is specified.
• Contains the EU-wide, standardised, alphanumerical codes assigned to the technical data, so that the German registration certificate can be converted without problems into the registration document prescribed in non-member European countries for registration there.
• Contains a field for documenting temporary or final immobilisation of the vehicle, and is therefore no longer withdrawn in the event of temporary or final immobilisation.

Registration certificate part II (vehicle log book)

• Contains the note that the holder of the registration certificate is not identified as the owner.
• Contains only the current and, if applicable, the last vehicle owner; the actual number of previous owners is shown numerically.
• Contains only a small percentage of the technical vehicle data.
• No longer serves to document temporary vehicle deregistration. The vehicle and body type specified under number 1 in the old vehicle documents will not exist in the future. In the new documents, this will be replaced by standardised EU vehicle classes with body type.

Introduction of the new registration documents will lead to barely any changes for the vehicle operator.

Like the old certificate of registration, the registration certificate part I (certificate of registration) must be kept in the vehicle and submitted to responsible persons on request.

It is not necessary for the wheel and tyre combination specified in the registration certificate part I (certificate of registration) to be fitted. All combinations approved according to the general vehicle type approval or EU type approval (see page 7) may be fitted.

The validity of a wheel/tyre combination which deviates from the general vehicle type approval or EU type approval must still be verified via an entry in the registration certificate part I (certificate of registration), an installation certificate based on a part certificate or general type approval for the wheel/tyre combination.

Manufacturers of motorized vehicles must apply for an EU operating permit for all class M1 passenger carrying vehicles.

A certificate is produced on the basis of this operating permit – the COC (Certificate of Conformity).

This document certifies that the vehicle complies with the EU operating permit (EU type approval) and can be registered in every EU country without an individual type approval.

The document will be issued for all vehicles that comply with the EU operating permit.

These vehicles have an EU type plate (black sticker) in the area of the driver’s door, or in the case of older vehicles, in the engine compartment.

The COC document has the same value as the registration document and therefore the original should not be carried on the vehicle.

The COC document contains the EU general type approval number and detailed technical information on the vehicle such as emissions classification and all the permitted wheel and tyre combinations.

Passenger cars licensed for road use in Germany need a general type approval for the issue of a vehicle title document.

The type approval is issued by the Federal Ministry for Transport in Flensburg following type inspection. This procedure was permitted until 31.12.1997 and, in exceptional cases, even after that.

Other member states of the European Union (EU) have different procedures for issuing a document similar to the German title document. Until 31.12.1997, each member state was entitled to issue its own national type approvals according to its own procedures.

Since 1.1.1998, all passenger cars licensed within the European Union must have a type approval corresponding to EU guidelines (see page 7). Vehicles licensed for road use with single-vehicle approval according to § 21 StVZO in Germany are excepted.

This means the same guidelines apply to all vehicle manufacturers. This makes it easier to trade across national borders within the EU.

Official type approval, sales or trade designation

In the following table, all VW vehicles which already have EU type approval are listed in the column “EU type”. All VW vehicles which were granted type approval according to the procedure valid up to 31.12.97 are listed in the column “General type”.

If entries appear in both columns “General type” and “EU type”, there are vehicles of this model which are approved by both StVZO and EU guidelines. In this case, the first step is to determine exactly what type of vehicle you have. There are two possibilities:

1. possibility

The last page of the vehicle title includes the field „Certified holder of a general type approval/EEC type approval“. Either the general type approval number of the EU type approval number is entered here, assuming it is the original vehicle title document. This is the case only if the vehicle was not deregistered in the past for longer than 12 months.

2. possibility

Check whether the general type approval number or the EU type approval number is entered on the vehicle identification plate.

Here are the identification markings found on the tyre sidewall:

1. Size code: e.g. 205/55 R 16 (refer to page 10 for more information).
2. Position of TWIs (Tread Wear Indicators):
3. Manufacturer (trade name):
4. Construction:
   • Radial – radial cord direction in carcass
   • Tubeless – code for tubeless tyres
5. Load capacity index / speed rating: e.g. 91 (refer to page 11 for more information) or H (refer to page 10 for more information).
6. Specified direction of rotation/installation for tyre:
7. Maximum permissible load: Data for North America.
8. Maximum permissible tyre pressure: Data for North America.
9. Number of plies in the centre of the tread and in the sidewalls, as well as information about the material:
10. E number = Approval number: Tyre fulfills European guidelines.
11. Manufacturer code / date of manufacture:
    • Identification number for manufacturer’s plant, tyre size and tyre model
    • Tyre ageing / date of manufacture (refer to page 13).
12. DOT – Department of Transportation: Tyre fulfils standards of the Department of Transportation of the United States of America.
13. Marking for Brazil:
14. Marking for China:
15. Country of origin: e.g. manufactured in Germany (Made in Germany).
16. Safety reference for use or fitting of tyre:
17. Relative expected service life – abrasion resistance: based on a US standard test.
18. Rating of wet-braking traction, A, B or C: According to a US test.
19. Rating of temperature resistance, A, B or C: According to a US test.
20. Identifying tyres with run-flat properties:
    • e.g. self-supporting run-flat
    • Identifying tyres with run-flat properties (refer to page 55).
21. Tread pattern: e.g. ContiPremiumContact.

Tyre dimensions are explained as follows:

1 – Tyre width

2 – Aspect ratio in %

3 – Code for tyre construction „R“ indicates radial

4 – Rim diameter designation

5 – Load rating code/load index (LI)

6 – Speed rating code

7 – Winter tyre/code for all-season tyre

Speed rating / maximum speed

The load rating code/load index (LI) provides information about the maximum load that the tyre can bear. The load rating is included in the size designation of the tyre (e.g. 195/65 R 15 91T). It is indicated on the tyre as a code according to ETRTO. The following table shows the load rating codes used at VW with the corresponding load capacity of the tyres.

The speed rating (e.g., “T”) following the size of the tyre (e.g., 185/65 R14 14 “T”) indicates the maximum permitted speed (vmax) of the tyre.

The tyres for the vehicle must be selected so that their maximum permitted speed is greater than the maximum speed that the vehicle (“based on model”) can attain.

If the vehicle has a national type approval, the maximum speed for the vehicle is calculated as follows:

Formula for vehicles with vmax up to 150 km/h:

vmax = 1.03 x v + 3.5 km/h (refer to page 12)

Example: Specified maximum speed v = 145 km/h

vmax = 1.03 x 145 km/h + 3.5 km/h = 152.85 km/h

In this example, a tyre with the speed rating “Q” or higher must be used.

Formula for vehicles with vmax above 151 km/h:

vmax = 1.01 x v + 6.5 km/h (refer to page 12)

Example: Specified maximum speed v = 163 km/h

vmax = 1.01 x 163 km/h + 6.5 km/h = 171.13 km/h

In this example, a tyre with the speed rating “S” or higher must be used.

If your vehicle has an EC type approval, the maximum speed for all vehicles is calculated as follows:

vmax = 1.05 x v (refer to page 12)

Example: Specified maximum speed v = 172 km/h

vmax = 1.05 x 172 km/h = 180.60 km/h

In this example, a tyre with the speed rating “T” or higher must be used.

It is permitted to use tyres with a higher speed rating. The same applies to tyres with a higher load index.

Note: For the letter “v”, enter the maximum speed given in field “T” of part I or II of the registration document or under number 6 of the vehicle documentation. This calculation is necessary because all vehicles, for technical reasons, achieve different maximum speeds within a legally permitted tolerance.

Undulations are slight wavy irregularities in the tyre sidewall. They run from the bead towards the shoulder of the tyre. These parts appear in the figure (refer to page 41).

The cause is the accumulation of material at the joints of the tyre components.

Undulations have no effect on:

• Safety,
• Service life,
• Handling or
• Other characteristics of the tyre.

Undulations are visible to varying extents. It is not necessary to inspect the tyre or remove it from the rim.

Modern steel belted tyres are constructed with single-ply side walls to save weight. The sidewall components consist of long strips before they are joined together to form a tyre. They must overlap at the joints. Consequently, slight irregularities or waves are created in the area of the overlapping parts. The overlaps are easier to see from the outside due to the single-ply construction.

The conditions for tyre storage have to be:

• dark,
• dry,
• cool and
• ventilated

in the tyre storage room.

WARNING: Stored tyres must not come in contact with fuel, oil, grease or chemicals under any circumstances. Otherwise, the material in the tyre will be damaged by chemical reactions which are not always visible. As a result, dangerous situations can occur when the car is driven.

Of course, tyre damage occurs only if the tyre is in contact with the chemical for a relatively long time. If a few drops of fuel land on a tyre during a fill up, this is of no concern.

Storage of tyres:

Complete wheels:

Tyres mounted on wheels can be stored flat, stacked one upon the other. In this case, it is important to ensure that the tyres are clean and dry. The inflation pressure should be increased to a maximum of 3 bar.

Tyres without wheels:

Tyres without wheels are best stored standing vertically. If tyres lie stacked for longer periods of time, they will be pressed together with a substantial force. The tyres will then be more difficult to fit, as they do not sit on the bead seats. If tyres are stored standing vertically, it is recommended to turn them every 14 days to avoid flat spots.

Tyres age as a result of physical and chemical processes, which can impair the function of the tyres. Tyres which are stored for longer periods of time harden and become brittle faster than tyres which are constantly in use on a vehicle. Older tyres may develop hairline cracks as a result of ageing. When tyres are in regular use, the constant flexing activates softeners in the rubber, preventing hardening and the development of cracks.

It is therefore important to take into account not only the tread depth, but also the age of spare tyres, stored tyres and tyres which are not permanently in use. The tyre age can be determined from the DOT designation, which includes the production date of the tyre.

Example of a DOT number to 31.12.1999:

In this example, the production date is the 50th week of 1999.

Example of a DOT number from 01.01.2000:

In this example, the production date is the 1st week of 2000.

Recommendation:

• It is recommended not to use summer and winter tyres which are older than 6 years anymore. The original properties deteriorate due to the aging process. Winter tyres especially lose their adhesion properties.
• When new tyres are fitted, the spare tyre may also be used if it is in flawless condition and is not more than 6 years old. The age of the tyre has a great influence on the high-speed capability of the tyre. It is possible to combine a spare tyre which is several years old with new tyres; however, this can have an adverse influence on car handling.
• Tyres are constantly being further developed, which can lead, for example, to slight changes in the rubber compound, even if the tyres are of the same make, size and tread pattern.
• All VW vehicles are factory-fitted with four identical tyres and wheels.

Front-wheel drive vehicles:

• For reasons of safety, tyres of the same make and with the same tread pattern should be mounted on one axle.

Four-wheel drive vehicles:

• Vehicles with four-wheel drive must always be equipped with four wheels with tyres of the same size, construction, tread pattern and make.

Renewing tyres:

Tyres must always be renewed when:

• the legal minimum tread depth of 1.6 mm is reached,
• there is visible mechanical damage.

As of 01.05.2006, a change to the German road traffic regulations (StVO) came into force which caused the following supplement to be made: “The equipment in motor vehicles has to be adapted to the weather conditions. In particular, this includes suitable tyres and antifreeze in the windscreen washing system.”

Please point out to customers that, since May 1st 2006, they are legally obliged to adapt their vehicle’s equipment, particularly the tyres, to winter weather conditions.

For driving in winter, we recommend that the vehicle be equipped with winter tyres in the sizes recommended in table 2 of the parts certificates.

As a basic rule:

All tyre sizes listed in the vehicle documents can also be used as winter tyres.

The handling characteristics may be affected by the use of winter tyres and the possible change in the dimensions of the wheel and tyre. Therefore, when using winter tyres, you must adapt your speed to the changed handling characteristics and to the road conditions.

To achieve the best possible handling, winter tyres must be fitted on all wheels.

If the vehicle is equipped with rims other than the factory-fitted rims, you must take the following into consideration when you fit winter tyres:

• Wheels and wheel bolts are matched.
• Whenever the wheels are changed, corresponding wheel bolts of the correct length and with the correctly shaped tapered seats are used¹⁾. The secure fit of the wheels and the functioning of the brakes depends this.
• The suitability of winter tyres with less than 4…5 mm tread depth for winter operation is limited.
• Some countries require winter tyres to have a tread depth of at least 4 mm.
• We recommend that winter tyres be replaced after no more than six years. The special „winter properties“ of these tyres decline with age, regardless of how much they are used.

¹⁾ A spherical cap is the curved surface of a section of a sphere cut by a plane. You can see a spherical cap on the wheel bolt and in the wheel (rim) in the tapped hole for the wheel bolt.

Vehicles with tyre pressure control:

On vehicles with tyre pressure control, the tyre inflation pressure has to be reset or matched when changing over between summer and winter tyres (refer to Workshop manual – Running gear – for relevant model).

The tyre industry now supplies winter tyres with speed symbol “V”. But only under certain conditions may these tyres be used up to the maximum permitted speed vmax = 240 km/h.

Vehicles with V tyres:

Vehicles requiring V tyres according to the vehicle’s title document can use winter tyres with speed symbol V without restriction at speeds up to vmax = 240 km/h.

Vehicles with W, Y or ZR tyres:

Under certain circumstances, vehicles requiring W, Y or ZR tyres according to the vehicle’s title document may not be driven at speeds of vmax = 240 km/h.

Why?

V summer tyres and V winter tyres without special identification (refer to page 16) have 100 % of their maximum load capacity (as specified by their load index “LI”) only up to speeds of 210 km/h.

Speeds above 210 km/h are possible with V winter tyres only if the maximum load of the tyres is not exceeded. The load capacity of the tyres decreases as the speed increases.

The maximum permitted axle load and the maximum achievable speed of some VW vehicles are so high that the load capacity of the V tyres is not sufficient for speeds of up to 240 km/h.

example: Tyre 205/55 R 16 91 V

The load index (LI) 91 certifies that this tyre has a load capacity of 615 kg per tyre at up to 210 km/h.

At a speed of 240 km/h, this tyre can carry a load of only 560 kg, i.e. the axle load may not exceed 1120 kg.

The Passat Estate V6 4Motion has a permitted axle load of 1150 kg and an achievable maximum speed of 232 km/h. This vehicle may only travel at speeds of up to 230 km/h with V winter tyres.

This applies to all V winter tyres without special markings.

V winter tyres marked XL have a higher load capacity than V winter tyres without this code.

XL V winter tyres allow a higher speed, but this does not mean that the top speed of a V tyre is 240 km/h for every VW car.

The same conditions apply to these tyres as to V winter tyres without a special code.

Tyre pressure for Extra Load V tyres:

Extra Load V winter tyres generally require 0.2 bar greater pressure (this does not apply for the Phaeton 2003 >).

The following table (refer to page 16) shows how fast VW cars may drive with V winter tyres, depending on their respective axle load.

The table below shows how fast VW cars may drive with V winter tyres, depending on their respective axle load.

Some tyre manufacturers have for some time replaced the designation “Reinforced” with the designation “Extra Load”. This designation has long been standard in non-European countries. Technically, there is no difference between them. Some tyre manufacturers also use the designation „XL“ for Extra Load tyres.

Tyres with the designation „Reinforced“ or „Extra Load (XL)“ are of equal quality.

Tyres must always be renewed when:

• the legal minimum tread depth of 1.6 mm is reached,
• there is visible mechanical damage.

Snow chains must be fitted to driven wheels only.

On most four-wheel drive vehicles, snow chains may be used only on the front wheels, but on the Touareg, also the rear wheels.

It is not possible to use snow chains with all wheel and tyre combinations. Notes on this can be found in the vehicle tables of the parts certificate.

If no particular type of snow chain is specified, then small-link chains may be used. These, including the chain fastener, may not protrude more than 15 mm beyond the wheel’s tread and the inner wall.

On some models, only special, small-link chains are possible with certain wheel and tyre combinations. Notes on this can be found in the vehicle tables of the parts certificate.

The maximum speed permitted by law when driving with snow chains is 50 km/h.

Snow chains should be removed when there is no snow on the road. There is no point in having them on the wheels, as they adversely affect the vehicle’s handling. It causes unnecessary stress on the tyres and above average wear on the chains.

The following factors influence a tyre’s service life to varying degrees.

Driving style:

• Speed (refer to page 20)
• Braking (refer to page 20)
• Acceleration (refer to page 21)
• Cornering (refer to page 21)

For more information about driving style, refer to page 20.

Maintenance:

• Tyre pressure (refer to page 21)

For more information about maintenance, refer to page 21.

Environment:

• Road surface
• Ambient temperature and climate

Vehicle:

• Weight
• Dynamic toe and camber settings

Tyre use:

• Speed range
• Wet or dry

Tyre type:

• Winter or summer

I. Steady driving without deceleration or acceleration:

II. Braking (driving style):

Most wear occurs during braking.

Example: Braking from a speed of 50 km/h

²⁾ g = Freefall acceleration: 9.81 m/s²

³⁾ A deceleration of 0.4 x g corresponds to heavy braking.

III. Acceleration (driving style):

Wheel slip occurring during driving off gently is approximately the same as that occurring during driving at a constant speed of 100 km/h.

Example:

IV. Driving through curves (driving style):

A »sporty« driving style and driving at higher speeds in curves also cause greater wear.

In practice, this means that wear is increased 16-fold when the cornering speed is doubled. This is the price that has to be paid for going faster.

Example: Driving through a curve with a radius of 150 m

⁴⁾ g = gravitational acceleration: 9.81 m/s²

The vehicle’s weight causes the tyre’s contact patch to flatten. This causes the tread and the entire bracing plies of the tyre continually to be deformed when a tyre is rolling. Low tyre pressure causes greater deformation, resulting in greater warming and increased rolling resistance. This then leads to increased wear and poses a greater safety risk.

Excessive tyre pressure will lead to increased wear around the centre of the tyre’s tread and to poor rolling comfort. We recommend always to maintain the tyre pressure specified by the manufacturer.

Note:

• The diagrams shown are not applicable in all cases.
• They are intended merely to give an idea of the wear rates of tyres on the front and rear axles and with front-wheel drive and four-wheel drive.
• The tyre service life may differ significantly, depending on operating conditions and running gear.

Diagram 1: Tread depth versus tyre life for vehicles with front-wheel drive and V-rated tyres

• P – Tread depth
• S – Mileage covered
• 1 – Front axle
• 2 – Rear axle

Diagram 2: Tread depth versus tyre service life for vehicles with four-wheel drive and V-rated tyres

• P – Tread depth
• S – Mileage covered
• 1 – Front axle
• 2 – Rear axle

Diagrams 1 and 2 show that the tread on a new tyre wears faster than that on a heavily used tyre. Because the wear curve is not linear, it is not possible to estimate the tyre’s expected life on the basis of wear after a distance of 5,000 km.

On front-wheel drive vehicles, the front tyres have to transmit not only the steering and driving forces, but also the greater part of the lateral and braking forces. This causes the front tyres on front wheel drive vehicles to wear much faster than the rear tyres. Even tyre wear can be achieved by rotating (interchanging) the front and rear tyres on a regular basis. Rotating wheels (refer to page 66).

When wheel alignment is checked, include the wheel alignment test results in tyre complaint report.

Manufacturer’s tolerances can lead to a slight amount of taper (asymmetry) in the tyre carcass. The rolling tyre then develops a lateral force which acts directly on the wheel suspension, leading to self-steering of the vehicle. Strategic rotation of the wheels can compensate for this self-steering behaviour.

Conicity: Conicity is caused by a slight offset of the tread and/or the belt (amounting to a few tenths of a millimetre) relative to the geometric centre of the tyre. Conicity is not visible and cannot be measured with equipment available in the workshop.

Parts of a tyre:

1. Bead
2. Shoulder
3. Tread
4. Steel cord belt

A – Geometrical centre of tyre

B – Actual centre of belt. It can be offset to inside or outside.

Pulling to one side can be caused by the running gear. However, experience shows that in 90% of all complaints, the tyres cause pulling to one side.

Pulling to one side during normal driving:

On a straight, level road surface, the vehicle wants to pull to one side at a constant speed or with moderate acceleration. Force can be felt at the steering wheel.

Pulling to one side during fast acceleration:

Pulling to one side during fast acceleration is, in part, due to the basic design of vehicles with front wheel drive. Different friction levels at the left and right wheels or possible irregularities in the road surface (potholes) and consequently varying road adhesion have a substantial influence on the handling characteristics. This does not constitute a complaint which is covered by the warranty.

Test conditions before and during the road test:

• Check all suspension components on the front and rear axles for damage.
• Check tyre pressure and correct if necessary.
• Check the tyres for external damage. Punctures, cuts, bubbles on the sidewalls, flat spots from braking and/or damage to the tread.
• Ask the customer if the tyre had been damaged by a nail or similar object and was repaired by a tyre dealer. It may be necessary to renew such tyres.
• Check tyres for even wear and tread depth.
• Are all tyres of the same type, manufacture and tread pattern?
• If the tyres are non-directional, ensure that all DOT classifications on the tyre face outwards. The wheels and/or tyres on the vehicle may have already been changed around at an earlier date.
• Is the make of tyre approved by the factory as original equipment?
• Perform the road test on a road which is level, straight and ungrooved and does not drop off to one side.
• Perform the road test with the customer under the conditions specified above. Ask the customer to demonstrate the problem.

Note: There must be no crosswind during the road test.

If the complaint is justified, we recommend rotating the wheels and tyres as described below. Before you begin, observe the following notes; otherwise your efforts may not have the desired effect.

Note:

• Mark the tyres before the first rotation, e.g. FR, FL, RR, RL.
• After rotating wheels or reversing the tyre on its rim, you must observe very carefully how the vehicle behaves during the road test. Note how and what was changed.
• Assess the intensity of or a possible change in the tendency to pull to one side.
• For this purpose, it is important that the road tests are always performed by the same person on the same road. It is best to drive the „test course“ in both directions.
• Replacing a tyre with a new tyre does not guarantee that pulling to one side will be eliminated. Therefore it is recommended as a first step to carry out the strategic rotation of the wheels as described below.
• If there are large differences in the tread depth of the tyres on the front and rear axles, the tyres with the deeper tread should always be mounted on the front axle.

As tyre damage can have serious consequences, you and the driver should regularly check the tyres to identify any problems at an early stage.

Damaged tyres cannot withstand driving conditions such as high speed, long distances, sporty driving, and so on.

Damage can be caused in a number of ways:

• Driving with insufficient tyre pressure
• Assembly error when tyres were fitted on rims
• Damage by embedding objects
• Ageing
• Improper storage

WARNING: Whenever a safety risk cannot be ruled out, the tyre must be renewed.

Cross section of a radial belted tyre:

1. Tread block
2. Tread groove
3. Tread
4. Nylon ply
5. Belt layers: Usually made of steel
6. Bead core: Consists of steel wires vulcanised into rubber. Ensures secure seating of the tyre on the rim.
7. Bead filler
8. Rim flange protection: Protects the rim and tyre from abrasion from, for example, contact with the kerb. Tyres with Maximum Flange Shield (or rim protector bar) are marked with the abbreviation MFS.

The nylon ply -4-, belt layers -5-, bead cores -6- and bead filler -7- form the carcass. The carcass is the „load-bearing structure“ of the tyre.

A swelling in the sidewall of the tyre indicates that the substructure of the carcass has been damaged.

Typical causes for such damage include, for example, driving over kerbs at a sharp angle.

Pinching the tyre in this way can damage the carcass. The substructure of the tyre is stretched so far that individual fibres in the carcass may be broken.

The extent of the damage depends on the speed of impact, the angle of impact, the tyre pressure, the axle load and the type of obstacle.

Pinch marks on tyre sidewall -arrows

Note:

• Driving over kerbs should be avoided.
• If driving over a kerb is unavoidable, do so very slowly and as square-on as possible.

Interior view of a tyre with a punctured carcass:

Due to a severe impact, the carcass was pinched on the wheel rim flange and is ruptured in the contact area.

Damage inside tyre due to impact injury (double rupture):

Double rupture -arrows- caused by pinching when a kerb was driven over. Often not detectable from outside.

9.4 Cuts

Cut caused by a sharp-edged obstacle -arrow

9.5 Damage caused by foreign bodies:

Driving over hard, pointed objects like nails, screws and the like can pierce the tyre. This always leads to tyre damage.

Damage due to embedded foreign body:

Often, the object -marking- is so securely embedded in the tyre that it will not free itself even at higher speeds. Consequently, it can act as a plug and seal the tyre relatively well. This results in a gradual loss of pressure, which the driver will not notice immediately, but which can lead to sudden and complete tyre failure.

Note: No repair should be attempted on a steel-belted tyre of which the structure has been punctured by a foreign body.

9.6 Loss of air from tyre:

If the customer complains of a loss of air from a tyre, it is essential that you check for embedded foreign bodies.

Note: No repair should be attempted on a steel belted tyre of which the structure has been punctured by a foreign body.

Corrosion can develop on the steel wires. This will always lead to the separation of the rubber from the steel belt. Generally, one cannot determine when the foreign body was embedded. The tyre structure may already have been damaged as a result of driving with insufficient tyre pressure. Damaged belt wires will sooner or later lead to separation of the rubber from the steel belt. As a result, the tyre can fail completely at some point long after the tyre was first damaged. Tyre damage caused by foreign bodies is not covered by the warranty.

The tyre pressure must be checked regularly. We recommend checking tyre pressure every two weeks. The correct tyre pressure is especially important during long trips or if a heavy load is to be carried. A sporty driving style also requires correct or even slightly increased tyre pressure.

The slow loss of tyre pressure is especially problematic because even experienced drivers often do not notice it. Insufficient tyre pressure and the related increase in flexing (internal friction) cause the tyre material to heat up considerably and may lead to the separation of the various components and rubber compounds. In the end, the tyre is usually destroyed completely (refer to page 50).

The cause for the slow pressure loss cannot always be determined because the tyre is severely damaged and components of the tyre are missing.

The most common causes for tyre failure are minor external damage, a defective valve or a leaking rim due to corrosion or damage.

Excessive heating due to driving with substantially insufficient tyre pressure (refer to page 51) led to overheating and subsequent separation of the carcass from the rubber material -arrows-. The tyre shown here was periodically driven with an inflation pressure which was insufficient for the load. Typical evidence for this is the circumferential scuffing along the bead caused by the wheel flange and also the discolouration. Small, furrowed creases are visible along the inside of the sidewall.

When the tyre rolls, strong shear forces develop between the layers of steel cord, especially at the ends of the belts.

Tyres with wide, circumferential furrows near the bead: Wide, circumferential furrows near the bead -arrows- indicate that the tyre was driven with insufficient pressure. Driving a vehicle with insufficient tyre pressure or ignoring or not recognising tyre damage can have serious consequences. The tyre can no longer withstand the forces which develop when the vehicle is driven. The defects mentioned above severely restrict the function of the tyre. The rubber compounds separate, which results in the partial separation of tyre components or even its complete destruction.

The graph shows the temperature development of a tyre at a speed of 180 km/h.

• A – When specified tyre pressure is maintained, the temperature will remain stable.
• B – Danger zone: When tyre pressure is 0.3 bar below specification, the temperature rises to above 120° C at higher speeds.
• C – Critical temperature threshold: A tyre defect will develop.

T – Temperature in °C

t – Travel time in minutes

Bead core broken during tyre inflation.

Modern radial tyres for passenger cars are mounted only on safety rims. Safety rims have a hump -1- running along the bead seat.

1. Hump (double hump H 2), extended double hump (EH2)
2. Rim flange
3. Inner bead seat (e.g. tapered bead seat)
4. Rim
5. Wheel
6. Well
7. Outer bead seat (e.g. tapered bead seat)

The hump prevents the tyre from being pressed out of the bead seat during travel with insufficient tyre pressure.

When the tyre is inflated, the bead of the tyre may not slip completely over the outer rim hump.

In this case, there is a danger of the bead core becoming overstretched if the tyre pressure is too high. The steel wires would then rupture partially or completely. A broken bead core cannot be detected from the outside.

Special requirements for tyres with run-flat properties:

Wheel rims with a raised double hump (Extended Hump EH2) are prescribed for tyres with run-flat properties (reinforced side walls) (refer to page 57). The raised double hump prevents the deflated tyre from slipping off its seat on the wheel rim when the tyre is run deflated.

Note: To avoid damage, always observe the notes/instructions when fitting/removing tyres with run-flat properties (refer to Running gear, axles, steering; Rep. gr. 44; Fitting and removing tyres with run-flat properties).

WARNING:

• Tyres with damaged bead cores are not seated safely and securely on the rim. Such tyres are a safety risk!
• In addition, there is a risk of the partly broken bead core breaking apart during continued operation and the tyre could suddenly tear open. If the bead core breaks during inflation, the carcass will also be destroyed.

The following errors, which may occur when tyres are fitted, can lead to severe tyre damage:

• If the opposite tyre bead is not seated completely in the rim well when the upper bead is rolled in on the tyre fitting machine (refer to page 52).
• If the fitting head is improperly adjusted.
• If the edge of the fitting roller rolls onto the bead.
• If the guide rollers are worn or have sharp edges.

Split tyre bead:

In these cases, the bead, which is under great tension, can be cut into in the direction of rotation, split and/or be pinched off down to the core wire.

It is often possible to identify the tracks of the guide roller as it was applied or ran off where the damage occurred.

Note: Both tyre beads as well as the bead seats must always be coated with assembly paste.

If fitting damage remains undetected, there is a danger that the tyre will fail later during operation.

THEREFORE!

• Never fit a tyre without using assembly paste.
• Do not allow the bead seating pressure to exceed 3 bar.
• Do not allow the tyre inflation pressure to exceed 4 bar.
• When the tyre has been fitted, reduce the tyre pressure to the specified value.

Tyres with run-flat properties have reinforced side walls when comparing them with normal tyres. This reduces the slippage of the side walls and prevents the tyre flanks sticking when the tyres are run deflated. This ensures the vehicle remains controllable and the vehicle has almost normal driving characteristics. The alleviates the necessity to fit the spare wheel in dangerous conditions e.g hard shoulder of a motorway or in bad weather conditions.

A deflated tyre can be driven further to the next workshop (approx. 50 km (approx. 30 miles)) at a suitable speed (max. 80 km/h (max. 50 mph)) and in suitable driving style for the conditions, see Owner’s wallet.

After checking the respective wheel, the responsibility lies with the driver to decide if it is safe to drive further with the deflated tyre.

-I- Tyres with normal air pressure

1. Tyres with run-flat properties (reinforced side walls -red-)
2. Normal tyres

-II- Deflated tyre

When a normal tyre -2- deflates, the side walls are pressed against the wheel rims. The side walls heat up extremely or stick and are therefore destroyed when the tyre is deflated. Tyres with run-flat properties -1- are supported on the reinforced side walls (-red-). A special tyre mixture and the reduced walkability of the reinforced side walls reduces the heat created when the tyre is run and the vehicle remains controllable.

Note: Please note the special requirements when using tyres with run-flat properties (refer to page 55).

Caution: Retrofitting run-flat tyres to VW models may only be undertaken if the tyres are fitted as standard or they are available as an option.

These tyres may only be used on vehicles with a tyre pressure monitoring system as a pressure loss in the tyres is not always visible. This system warns the driver when an inflation pressure is less than a certain inflation pressure.

Permitted are:

• Direct measuring systems (refer to Running gear, axles, steering; Rep. gr. 44; Tyre pressure monitor)
• Indirect measuring systems (refer to Running gear, axles, steering; Rep. gr. 44; Tyre pressure monitor)

Tyres with run-flat properties may only be fitted on disc-type wheels with raised double hump (Extended Hump – EH2) (refer to page 57).

Radial and lateral runout occur when the wheel and tyre do not run absolutely true. For technical reasons, 100% true running is not possible. Therefore, the manufacturers of these components allow a precisely determined tolerance.

Mounting the tyre in an unfavourable position on the wheel can cause the maximum allowed tolerance for wheel with tyre to be exceeded.

The table shows the maximum permissible tolerances for a wheel with mounted tyre.

Checking lateral runout:

• Preload tyre gauge about 2 mm.
• Set tyre gauge against sidewall of tyre.
• Slowly rotate the wheel.
• Note the smallest and the largest dial readings.

Note: If the difference is greater than 1.3 mm, the lateral runout is too great. In this case, you can reduce lateral runout by match mounting the tyre (refer to page 38).

Extreme values on the tyre gauge due to small irregularities in the rubber may be disregarded.

Checking radial runout:

• Preload tyre gauge about 2 mm.
• Set the tyre gauge against the tyre tread.
• Slowly rotate the wheel.
• Note the smallest and the largest dial readings.

Note: If the difference is greater than 1 mm, the radial runout is too great. In this case, you can reduce radial runout by match mounting the tyre (refer to page 38).

• Mount the wheel on the wheel balancer.
• Use the wheel balancing machine centring system -VAS 5271-.
• Preload tyre gauge about 2 mm.
• Slowly rotate the wheel.
• Note the smallest and the largest dial readings.

S – Lateral runout

H – Radial runout

• Compare the measured values with the specifications in the table (refer to page 37).

Note: Extreme values on the tyre gauge due to small irregularities may be disregarded.

When radial or lateral runout of the wheel and tyre coincide, the imbalance of the wheel is amplified by the tyre. For technical reasons, 100% true running is not possible (refer to page 36).

Before match mounting the used wheels which are fitted on the vehicle, run the tyres warm. This will eliminate any flat spots caused by storage or handling (refer to page 39).

Procedure for match mounting:

• Deflate the tyre.
• Press the tyre beads off the rim flanges.
• Coat the tyre bead all round with tyre fitting paste.
• Rotate the tyre 180° relative to the wheel.
• Inflate the tyre to approx. 4 bar.
• Mount the wheel with tyre on the wheel balancer.
• Check true running, that is, radial and lateral runout.

Note:

• If the specified values for radial and lateral runout are not exceeded, the wheel can be balanced to 0 grams. Specified values appear on (refer to page 36).
• If the radial and lateral runout is not within the specifications, the tyre must be rotated again.
• Deflate the tyre and press the tyre beads off the rim flanges.
• Rotate the tyre 90° relative to the wheel (1/4 of a turn).
• Inflate the tyre to 4 bar again and check true running.

Note:

• If the specified values for radial and lateral runout are not exceeded, the wheel can be balanced to 0 grams.
• If the radial and lateral runout is not within the specifications, the tyre must be rotated again.
• Press the tyre off the rim flanges again as described above.

The term flat spot describes a type of wear where one patch or spot of the tyre has become flat. Flat spots caused by storage or handling also cause vibration in the same way as incorrectly balanced wheels do. It is important that flat spots on the tread caused by storage or handling are identified as such.

Flat spots caused by storage or handling cannot be balanced and they can reoccur at any time due to various circumstances. Flat spots caused by storage or handling can be eliminated without complicated special tools. This does not apply to flat spots caused by hard braking (refer to page 30).

Note: Flat spots caused by hard braking cannot be repaired. Such tyres must be renewed.

Reasons for flat spots caused by storage or handling:

• The vehicle has been left standing in one place without being moved for several weeks.
• The tyre inflation pressure is too low.
• The vehicle was placed in a paint shop drying booth after being painted.
• The vehicle was parked with warm tyres in a cool garage or similar for a long period of time. In this case, a flat spot from standing may even occur overnight.

Eliminating flat spots caused by storage or handling:

• Flat spots caused by storage or handling cannot be eliminated from the tyre using workshop equipment.
• Flat spots caused by storage or handling can be removed only by running the tyres warm.
• The method described below is not recommended in cold and wintry weather.

Requirements and conditions:

• Check and, if necessary, correct inflation pressures.
• Drive the car on a motorway where possible.
• Traffic and road conditions permitting, drive a 20 to 30 km stretch at a speed of 120 to 150 km/h.

WARNING:

• Do not endanger yourself or other road users during this road test.
• Observe the highway code and speed limitations in force when performing the road test.

• Raise the vehicle immediately following the road test.
• Remove the wheels from the vehicle.
• Balance the wheels on a stationary wheel balancer (refer to page 33).

Clamp wheel into wheel balancing machine

Note: When balancing tyres, remember that cleanliness is absolutely essential, as indeed it is in the case of any other repair work you carry out. Only then can you attain a flawless result! Dirt and rust in the area of the contact surfaces and centre of the wheel distort the result.

• Clean the contact surfaces, the centre of the wheel and the recess on the inside of the wheel before mounting the wheel on the wheel balancer.
• Mount the wheel with tyre on the wheel balancer.

Note: To clamp the wheel, use e.g. centring system for wheel balancing machines -VAS 5271-. This ensures that the wheel is 100% centred and that the wheel will be clamped without damage!

• The wheel cannot be centred 100% with conical clamping elements on the wheel balancing machine.
• A deviation of 0.1 mm from the centre results in an imbalance of 10 grams at the wheel’s rim.

Procedure for balancing wheels and tyres:

• Rotate wheel and tyre on wheel balancer.
• Check that the indicator lines on the sidewall of the tyre near the rim flange run evenly.
• Check that the body of the tyre runs evenly while the wheel and tyre are rotating.

Note: If one-sided wear, flat spots from braking or severely washed out spots are apparent, balancing cannot achieve smooth running. In this case, the tyre must be renewed.

• Check the true running of the wheel and tyre. If the wheel and tyre do not run true although there are no flat spots, radial or lateral runout may be the cause.
• Check the wheel for radial or lateral runout (refer to page 36).
• If radial and lateral runout are within the specified tolerance, balance the wheel and tyre.

Note:

• More than 60 grams of weight per tyre should not be used.
• If more weight is required, you may be able to achieve smoother running by match mounting the tyre and rim. Match mounting tyres (refer to page 38).
• The wheel balancer display should indicate 0 grams.
• As an alternative to match mounting, you could use the vibration control system -VAS 6230- (refer to page 35).

Bolt the wheel to the vehicle:

• First hand-tighten the lowest wheel bolt to about 30 Nm.
• Then tighten the remaining wheel bolts diagonally to about 30 Nm. This process ensures that the wheel is centred properly on the hub.
• Lower vehicle onto its wheels.
• Now use a torque wrench to tighten the wheel bolts diagonally to the specified torque.

Perform road test:

• After balancing the wheels and tyres, perform a road test.

Perform a road test to determine whether a vehicle is pulling to one side and if so, which side. If the vehicle pulls to one side (refer to page 42).

When wheel alignment is checked, include the wheel alignment test results in tyre complaint report.

Manufacturer’s tolerances can lead to a slight amount of taper (asymmetry) in the tyre carcass. The rolling tyre then develops a lateral force which acts directly on the wheel suspension, leading to self-steering of the vehicle. Strategic rotation of the wheels can compensate for this self-steering behaviour.

Conicity: Conicity is caused by a slight offset of the tread and/or the belt (amounting to a few tenths of a millimetre) relative to the geometric centre of the tyre. Conicity is not visible and cannot be measured with equipment available in the workshop.

Parts of a tyre:

1. Bead
2. Shoulder
3. Tread
4. Steel cord belt

A – Geometrical centre of tyre

B – Actual centre of belt. It can be offset to inside or outside.

Exaggerated for clarity.

1. Offset of belt and tread
2. F1 – Unequal vertical wheel forces
3. F2 – Unequal vertical wheel forces
4. Fk – Conicity force

The offset produces differences in stiffness at the inner and outer shoulders of the tyre, resulting in differing vertical wheel forces. Consequently, the belt or tread will not be pressed onto the road surface with the same force (F1, F2). A conical, or tapered, shape develops. The resulting force (conicity force Fk) can, depending on the speed, become so great that the vehicle then pulls to one side.

If the force Fk on one wheel of the axle is, for example, 50 Newton, and also 50 Newton on the other wheel, and both forces are exerted in the same direction, the forces are cumulated. Reversing a tyre on the rim can compensate for the lateral pull because the forces then act in opposite directions.

Because the direction in which the force of taper is exerted is not visible, only road tests and strategic rotation of wheels and tyres can establish which tyres cause the pulling.

The tyre consists of numerous components and materials which are vulcanized to form a single part at the end of a complicated manufacturing process. The result is differing production tolerances which make themselves noticeable through more or less strong lateral forces (conicity forces). These forces can also occur in new tyres.

Pulling to one side on front axle: Pulling to one side can be caused by the running gear. However, experience shows that in 90% of all complaints, the tyres cause pulling to one side.

One-sided wear, usually in conjunction with signs of scuffing on the ribs of the tread and in the fine grooves, always occurs when the tyres have been allowed to roll with an extreme tyre slip angle, causing them to »rub« on the road surface.

Driving fast on a stretch of road with lots of curves will cause increased wear, in particular on the outer shoulder.

A rounded outer shoulder on the tyre in conjunction with a particularly high degree of wear on the outer tread blocks indicates fast cornering. This wear pattern is influenced by driving style.

To optimise handling, the suspension is set to certain toe and camber values. Increased one-sided wear can be expected if tyres are allowed to roll under conditions which differ from those specified.

One-sided wear is especially likely if the toe and camber have not been set correctly. Moreover, there is a greater risk of diagonal washout.

Toe-out or negative toe-in: Distance between the front edges of the wheels -A- is greater than distance between the rear edges of the wheels -B- (-C- = direction of travel).

This wear pattern is found on the driven wheels of high-performance vehicles that are frequently driven long distances at high speeds.

At high speeds, centrifugal forces cause the tyre diameter to increase more in the middle of the tread than it does at the shoulder. This causes drive forces to be transferred to the road surface from the centre section of the tread. This is reflected in the wear pattern.

Effects of this kind can be especially pronounced on wide tyres.

It is not possible to counter this wear pattern by reducing the tyre pressure.

WARNING: For reasons of safety, the tyre pressure must not under any circumstances be reduced below the specified tyre pressure.

A more or less even tread wear pattern can be achieved by rotating the tyres between the driven wheels and non-driven wheels in good time.

Increased tread wear: The typical tread wear pattern of tyres run on the driven wheels of a high-performance vehicle. The increased wear in the centre section of the tread results from the extra load associated with centrifugal forces within the tyre and the transmission of drive forces.

Diagonal washout runs at an angle of approx. 45° to the circumference. It usually occurs at one point only, but can also occur at several points around the circumference of the tyre. Washout occurs almost exclusively on the tyres on the non-driven wheels, in particular at the rear left. Washout occurs very often on some models, while it poses no problem at all on other models. The effect is intensified by high toe-in values. Toe-in values in the region of the lower tolerance limits of the specified alignment values improve the wear pattern.

The most pronounced diagonal washout is often found in the area where the tyre components are joined.

Wheels with positive toe-in roll with a slip angle even straight ahead. This leads to a diagonal strain in the contact patch or footprint on the tyre/road surface. This wear pattern is intensified when tyre pressure is too low. To avoid such tread wear patterns, the toe-in values of the two rear wheels should be identical and the specified tyre pressures observed.

If washout is detected at an early stage, the wheels should be fitted on the drive axle. Deeper washout cannot be repaired.

Faulty adjustment: If a customer complains of „diagonal wear spots“, the toe adjustment must be examined. If toe-in is correct, the cause of the diagonal washout is very probably the tyre itself. Tyres with diagonal washout caused by incorrect wheel alignment are not covered by warranty.

Tyre noise that can be heard by the human ear is caused by vibrations which are transmitted by the air from the source of the sound to our ears. Of interest here are the noises caused by certain characteristics and effects of the rolling tyre (source of the sound). The cause of the noise is largely dependent on the combination of the road surface and tyres.

The structure and material of the road surface will greatly affect tyre noise. For example, the noise level on a wet road is much higher than on a dry road.

The pattern of the tyre tread also has a significant influence on tyre noise. Tyres with transverse grooves at an angle of 90° generate more noise than tyres with grooves running diagonally.

Small tread blocks are unstable. Their highly pronounced deformation agitates the air as the tyres roll. This creates vibrations in the air which cause tyre noise.

Wider tyres are louder. They need more tread channels to displace water. When the tyres roll, these tread channels displace the air, also creating vibrations in the air.

Further effects that also influence tyre noise:

• „Tyre vibration“ is the principal cause of tyre noise. It is caused by the columns of air in the tread channels being agitated.
• „Air pumping“ is the compression and expansion of the air caused by the deformation of the tread blocks as the tyre contact patch moves along the road surface.

Useful information regarding tyre noise:

Tyre noise is determined primarily by the tyres and the road surface.

The roughness, structure and material of the road surface influence tyre noise.

The widths of the tyre and the rim, among other things, influence tyre noise. Due to their larger contact area, wider tyres will cause more tyre noise than narrow tyres, as more air has to be displaced and more „mass“ is agitated to create vibrations.

A wider wheel rim will also cause a tyre to have a wider contact patch. The effect on tyre noise is thus very similar to that of a wider tyre. Moreover, the damping characteristics of the tyre may also be adversely affected by the wider wheel rim.

Tyre noise of a vehicle with front-wheel drive is more perceptible in the rear because wind and the engine noise are not as loud there.

Saw-tooth wear is a stepped wear pattern on the individual tread blocks (refer to page 30) that can cause increased tyre noise. The saw tooth is caused by uneven deformation of the tread blocks in the tyre’s contact patch. Saw-tooth wear is more pronounced on non-driven wheels than on driven wheels.

Pronounced saw-tooth wear occurs under the following conditions:

• toe-in values are too high
• tyre pressures are incorrect
• tread is coarse and open
• tyres are fitted on the non-driven axle
• very fast cornering

non-directional tyres: In the event of saw-tooth wear, the direction of rotation of the tyre must be reversed. If saw-tooth wear is especially pronounced and tyre noise has increased, interchange the tyres diagonally. This will reduce the saw-tooth effect.

On front-wheel-drive vehicles, this effect is intensified by the greater wear on the front axle.

Tyre noise will be somewhat louder immediately after the tyres have been interchanged but will return to a normal level after about 500…1,000 km have been driven.

Directional tyres: In the event of increased saw-tooth wear on the rear tyres – in particular on front-wheel drive vehicles – interchange the front and rear tyres. In the event of increased saw-tooth wear on the outer edges of the tyres on one axle, turn both tyres around on their rims. The left-hand wheel must then be fitted on the right side of the vehicle and the right-hand wheel on the left side.

Flat spots result from hard braking which causes the wheels to lock so that the rubber is worn off at the contact patch between the tread and the road surface. As the tyres slide over the road surface, friction generates heat, which reduces the tread material’s resistance to wear.

Not even the most wear-resistant tread compound can prevent the flat spots caused by extreme braking.

Even ABS-controlled brake systems cannot prevent brief locking of the wheels, and thus, minor flat spots.

The degree of such wear depends largely on the vehicle speed, the road surface and the load placed on the wheel. The following examples should make this clear.

If a vehicle is braked to a standstill on a dry surface with the wheels locked, the amount of rubber worn from the tyre will cover an area the size of a postcard and will have a thickness of:

• up to 2.0 mm from a speed of 57 km/h (23.8 m braking distance)
• up to 3.3 mm from a speed of 75 km/h (41.8 m braking distance)
• up to 4.8 mm from a speed of 92 km/h (71.6 m braking distance)

Flat spots in tread: Tyres with such damage must no longer be used and must be renewed.

There are numerous causes for vibration. Vibration can be caused by tyre wear, among other things. Tyre wear caused by driving is not always uniform across the entire tread of the tyre. This causes slight imbalances which affect the smooth running of a wheel which was previously exactly balanced.

Minor imbalances will not be felt at the steering wheel, but that does not mean that they are not there. They increase wear on the tyre, thus reducing the tyre’s service life.

Recommendation: To ensure optimal safety, smoothest possible running and even wear throughout a tyre’s service life, we recommend having the wheels and tyres balanced at least twice during the tyre’s service life.

Before you start balancing the wheels, the following requirements must be met.

• The tyre pressure must be correct.
• The tyre tread must not show one-sided wear and should be at least 4 mm deep.
• The tyre must not show any signs of damage, for example cuts, piercing, foreign bodies, etc.
• The wheel suspension, steering and steering linkage, including the shock absorbers, must be in perfect condition.
• You must have conducted a road test.

If a customer brings a vehicle to the workshop complaining about “vibration”, a road test is essential prior to balancing the wheels.

• This will give you information about the nature of the vibration.
• You will be able to determine in which speed range the vibration occurs.
• Raise the vehicle on a lifting platform immediately after the road test.
• Mark the positions of the tyres on the vehicle.

• Remove wheels from vehicle.
• Balance wheels.

Note: To clamp the wheel, use e.g. centring system for wheel balancing machines -VAS 5271-. This ensures that the wheel is 100% centred and that the wheel will be clamped without damage! The wheel cannot be centred 100% with conical clamping elements on the wheel balancing machine. A deviation of 0.1 mm from the centre results in an imbalance of 10 grams at the wheel’s rim.

• Rotate wheel and tyre on wheel balancer.
• Check that the indicator lines on the sidewall of the tyre near the rim flange run evenly.
• Check that the body of the tyre runs evenly while the wheel and tyre are rotating.

Note: If one-sided wear, flat spots from braking or severely washed out spots are apparent, balancing cannot achieve smooth running. In this case, the tyre must be renewed.

• Check the true running of the wheel and tyre. If the wheel and tyre do not run true although there are no flat spots, radial or lateral runout may be the cause.
• Check the wheel for radial or lateral runout (refer to page 36).
• If radial and lateral runout are within the specified tolerance, balance the wheel and tyre.

Note:

• More than 60 grams of weight per tyre should not be used.
• If more weight is required, you may be able to achieve smoother running by match mounting the tyre and rim. Match mounting tyres (refer to page 38).
• The wheel balancer display should indicate 0 grams.
• As an alternative to match mounting, you could use the vibration control system -VAS 6230- (refer to page 35).

• Bolt the wheel to the vehicle.
• First hand-tighten the lowest wheel bolt to about 30 Nm.
• Then tighten the remaining wheel bolts diagonally to about 30 Nm. This process ensures that the wheel is centred properly on the hub.
• Lower vehicle onto its wheels.
• Now use a torque wrench to tighten the wheel bolts diagonally to the specified torque.

Perform road test:

• After balancing the wheels and tyres, perform a road test.

Note: The imbalance should always be less than 20 grams before you change the balance weight. If necessary, remove the wheel bolts again. Rotate the wheel relative to the hub once more, turning it one or two wheel bolt holes further. Tighten the wheel bolts using the method described above.

Note: Do not try to reduce the imbalance using balance weights until the imbalance is less than 20 grams. Balance the wheels until the imbalance is less than 5 grams. Tighten wheel bolts to specified torque setting if you have not already done so.

WARNING: Always tighten wheel bolts to specified torque using a torque wrench!

Radial and lateral runout occur when the wheel and tyre do not run absolutely true. For technical reasons, 100% true running is not possible. Therefore, the manufacturers of these components allow a precisely determined tolerance.

Mounting the tyre in an unfavourable position on the wheel can cause the maximum allowed tolerance for wheel with tyre to be exceeded.

The table shows the maximum permissible tolerances for a wheel with mounted tyre.

Checking lateral runout:

• Preload tyre gauge about 2 mm.
• Set tyre gauge against sidewall of tyre.
• Slowly rotate the wheel.
• Note the smallest and the largest dial readings.

Note: If the difference is greater than 1.3 mm, the lateral runout is too great. In this case, you can reduce lateral runout by match mounting the tyre (refer to page 38).

Extreme values on the tyre gauge due to small irregularities in the rubber may be disregarded.

Checking radial runout:

• Preload tyre gauge about 2 mm.
• Set the tyre gauge against the tyre tread.
• Slowly rotate the wheel.
• Note the smallest and the largest dial readings.

Note: If the difference is greater than 1 mm, the radial runout is too great. In this case, you can reduce radial runout by match mounting the tyre (refer to page 38).

• Mount the wheel on the wheel balancer.
• Use the wheel balancing machine centring system -VAS 5271-.
• Preload tyre gauge about 2 mm.
• Slowly rotate the wheel.
• Note the smallest and the largest dial readings.

S – Lateral runout

H – Radial runout

• Compare the measured values with the specifications in the table (refer to page 37).

Note: Extreme values on the tyre gauge due to small irregularities may be disregarded.

When radial or lateral runout of the wheel and tyre coincide, the imbalance of the wheel is amplified by the tyre. For technical reasons, 100% true running is not possible (refer to page 36).

Before match mounting the used wheels which are fitted on the vehicle, run the tyres warm. This will eliminate any flat spots caused by storage or handling (refer to page 39).

Procedure for match mounting:

• Deflate the tyre.
• Press the tyre beads off the rim flanges.
• Coat the tyre bead all round with tyre fitting paste.
• Rotate the tyre 180° relative to the wheel.
• Inflate the tyre to approx. 4 bar.
• Mount the wheel with tyre on the wheel balancer.
• Check true running, that is, radial and lateral runout.

Note:

• If the specified values for radial and lateral runout are not exceeded, the wheel can be balanced to 0 grams. Specified values appear on (refer to page 36).
• If the radial and lateral runout is not within the specifications, the tyre must be rotated again.
• Deflate the tyre and press the tyre beads off the rim flanges.
• Rotate the tyre 90° relative to the wheel (1/4 of a turn).
• Inflate the tyre to 4 bar again and check true running.

Saw-tooth formation is a normal wear pattern, particularly if the driving style is very careful (refer to page 29). This can lead to increased rolling noise, which generally becomes better as the tread depth decreases. In the event of light saw tooth formation or if saw tooth formation is just starting, exchanging the wheels between axles is normally sufficient. In cases where saw tooth formation is very pronounced, the wheels have to be changed in accordance with (refer to page 29) so their direction of rotation is reversed.

Some tread patterns may create an impression of premature wear: if winter tyre sipes or channels in the tread are worn down, only compact profile blocks without patterns remain, thus giving the impression of a worn tyre. In this case, the remaining tread depth must be measured in each groove. If this is at or below the minimum tread depth, the tyre can continue to be used without restrictions. (In Germany, the minimum is 1.6 mm; it is recommended, and in Austria, required, that winter tyres that are worn down to 4 mm be used only in summer.)

This wear pattern is found on the driven wheels of high-performance vehicles that are frequently driven long distances at high speeds. At high speeds, centrifugal forces cause the tyre diameter to increase more in the middle of the tread than it does at the shoulder. This causes drive forces to be transferred to the road surface from the centre section of the tread. This is reflected in the wear pattern.

Effects of this kind can be especially pronounced on wide tyres.

It is not possible to counter this wear pattern by reducing the tyre pressure.

A tyre has to meet numerous requirements (refer to page 19). Different types of tyres meet these requirements to varying degrees. Depending on the conditions in which the tyres are used and on the type of vehicle, some requirements will be more important than others.

H, V, and Z tyres for „high-performance vehicles“ are expected to have good grip on wet and flooded roads. On the other hand, they cannot have such a long mileage expectancy as, for example, tyres with S or T ratings.

5.2 Requirements to be met by tyres:

• A – Wet braking properties
• B – Driving comfort
• C – Steering accuracy
• D – Driving stability
• E – Tyre weight
• F – Life expectancy
• G – Rolling resistance
• H – Aquaplaning

The pie chart illustrates to what extent the tyre meets the various requirements. It shows how the proportions of the requirements A to H can be distributed according to the construction of the tyre and the rubber mixture used. Improving one of the characteristics will have a negative effect on one of the others.

Example: An improvement in wet braking properties -A- leads to a reduction in driving comfort -B-, rolling resistance -G- and life expectancy -F-.

The life expectancy of passenger vehicle tyres does not just depend on the rubber composition and design of a tyre. The conditions for use, the vehicle-specific circumstances and driving style have a heavy influence on the service life of a tyre.

Modern vehicles with the appropriate engine allow a gentle, economical driving style but also an extremely sporty driving style. A tyre life of 5,000 to 40,000 km or more is possible.

Note: The driving style is the most important factor in determining the service life of a tyre.

5.3 Wear behaviour of high-speed tyres:

These tyres are designed for use at high speeds. The main objective in the development of this type of tyre is good grip on wet surfaces. The tread compositions do not have the same wear resistance as T and H tyres for lower speeds.

The expected life of high-speed tyres is therefore considerably lower under comparable operating conditions.

The following factors influence a tyre’s service life to varying degrees.

Driving style:

• Speed (refer to page 20)
• Braking (refer to page 20)
• Acceleration (refer to page 21)
• Cornering (refer to page 21)

For more information about driving style, refer to page 20.

Maintenance:

• Tyre pressure (refer to page 21)

For more information about maintenance, refer to page 21.

Environment:

• Road surface
• Ambient temperature and climate

Vehicle:

• Weight
• Dynamic toe and camber settings

Tyre use:

• Speed range
• Wet or dry

Tyre type:

• Winter or summer

Different wear on the front and rear axle is unavoidable depending on the driving style. This condition can be compensated for by swapping over the wheels from front to rear. The ideal opportunity to do this, for example, is during the seasonal change between winter and summer tyres. This change also has a positive side effect in that the tyres can wear down equally, meaning that a completely new set of tyres can be fitted. This prevents the use of tyres with different tread depths on both axles, which can have negative effects on road holding.

Saw tooth formation is a normal wear pattern, particularly where the driving style is very careful (refer to page 29). This can lead to an increase in rolling noise, which generally becomes better as the tread depth decreases. In the event of light saw tooth formation or if saw tooth formation is just starting, exchanging the wheels between axles is normally sufficient. In cases where saw tooth formation is very pronounced, the wheels have to be changed in accordance with (refer to page 29) so their direction of rotation is reversed.

Some tread patterns may create an impression of premature wear: if winter tyre sipes or channels in the tread are worn down, only compact profile blocks without patterns remain, thus giving the impression of a worn tyre. In this case, the remaining tread depth must be measured in each groove. If this is at or below the minimum tread depth, the tyre can continue to be used without restrictions. (In Germany, the minimum is 1.6 mm; it is recommended, and in Austria, required, that winter tyres that are worn down to 4 mm be used only in summer.)

The effective service life of a tyre can be determined only when the remaining tread depth has reached 2 mm (see diagrams, refer to page 22).

Note:

• The tread depth is measured in the main tread channels.
• Do not measure at the TWIs (Tread Wear Indicators).

Measure the tread depth in the main tread channel, at the points where the tyre is worn most heavily. The position of the TWIs can be seen at various points on the shoulder of the tyre (refer to Item 2, page 9).

A „Δ“ or the manufacturer’s „logo“ may appear in the place of „TWI“.

The bars of the TWI have a height of 1.6 mm. This is the minimum tread depth required by German law. Different values may apply in other countries.

The TWIs must not be included in the measurement. Tread depth should always be measured at the deepest point of the tread channel.

A – TWIs in the main tread channels

B – Main tread channels with TWIs -arrows

This is often caused by driving style, but can be the result of incorrect wheel alignment.

Distance between the front edges of the wheels -A- is greater than distance between the rear edges of the wheels -B- (-C- = direction of travel).

Distance between the front edges of the wheels -A- is less than distance between the rear edges of the wheels -B- (-C- = direction of travel).

To prevent one-sided wear, care must be taken to ensure that the wheel is set within the tolerance specified by the vehicle manufacturer. The most frequent deviation of the wheel alignment is caused by external influences, for example hard contact with the kerbstone when parking.

By measuring the axle geometry, you can check whether the wheel alignment is within the specified tolerances or whether it has to be corrected.

Using „suspension-lowering kits“ and/or alloy wheels that have not been recommended by VW may result in altered wheel positions which deviate from the specified alignment.

Even if the axle geometry is correct with the vehicle stationary during wheel alignment, the changed vehicle height and wheel positions can cause the wheel suspension to move differently during operation. Uneven wear is then unavoidable.

Unsuitable use of self-levelling adjustments on pneumatic suspension system: The use of the offroad level is recommended only for driving offroad. Permanent use of the offroad level during normal road operation can lead to increased tyre wear as the height of the wheel position is different to the road level.

The way to prevent one-sided tyre wear is to ensure the wheel alignment is correct on one hand and on the other hand to make sure the vehicle is used only for its intended purpose:

Regular servicing of the vehicle and tyres helps to prevent tyre wear. The following should be noted in particular with regards to this:

• The prescribed minimum tyre inflation pressures must be adhered to.
• Different wear on the front and rear axle depending on the driving style is unavoidable. This condition can be compensated for by rotating the wheels from front to rear. The ideal opportunity to do this, for example, is during the seasonal change between winter and summer tyres. This change also has a positive side effect in that the tyres can wear down equally, meaning that a completely new set of tyres can be fitted. This prevents the use of tyres with different tread depths on both axles, which can have negative effects on road holding.
• Saw tooth formation is a normal wear pattern, particularly if the driving style is very careful (refer to page 29). This can lead to increased rolling noise, which generally becomes better as the tread depth decreases. In the event of light saw tooth formation or if saw tooth formation is just starting, exchanging the wheels between axles is normally sufficient. If saw tooth formation is very pronounced, the wheels have to be changed in accordance with (refer to page 29) so their direction of rotation is reversed.
• Some tread patterns may create an impression of premature wear: if winter tyre sipes or channels in the tread are worn down, only compact profile blocks without patterns remain, thus giving the impression of a worn tyre. In this case, the remaining tread depth must be measured in each groove. If this is at or below the minimum tread depth, the tyre can continue to be used without restrictions. (In Germany, the minimum is 1.6 mm; it is recommended, and in Austria, required, that winter tyres that are worn down to 4 mm be used only in summer.)

Observe the notes regarding the recommended makes of summer tyres (refer to page 458).

Observe the notes regarding the recommended makes of summer tyres (refer to page 458).