SECTION 10 - WHEELS AND TYRES

CAUTION:

This vehicle will be equipped with a Supplemental Restraint System (SRS). An SRS

will consist of either seat belt pre-tensioners and a driver's side air bag, or seat belt

pre-tensioners and a driver's and front passenger's side air bags. Refer to

CAUTIONS, Section 12M, before performing any service operation on or around any

SRS components, the steering mechanism or wiring. Failure to follow the CAUTIONS

could result in SRS deplo yment, resulting in possible p ersonal injury or unnecessary

SRS system repairs.

CAUTION:

Whenever any component that forms part of the ABS or ABS/ETC (if fitted), is

disturbed during Service Operations, it is vital that the complete ABS or ABS/ETC

system is checked, using the procedure as detailed in 4. DIAGNOSIS, ABS or

ABS/ETC FUNCTION CHECK, in Section 12L ABS & A BS/ETC.

1. GENERAL INFORMATION

New wheels and wheel covers have been

introduced for VT Series vehicles.

The Executive VT Series Model with V6 engine

features 6.0J x 15 steel wheels with P205/65 R15

92H tubeless tyres and revised wheel covers.

Berlina models feature 6.0J x 15 alloy wheels with

P205/65 R15 92H tubeless tyres.

VT Series Calais have newly designed 7.0J x 16

alloy wheels and P215/60 R16 92H size tubeless

tyres.

VT ‘S' Models use the 7.0J x 16 alloy wheels

previously used on VS, ‘SS’ pack vehicles and

fitted with P225/50 R16 92V tyres.

VT ‘SS' Models have newly designed 8.0J x 17

alloy wheels and P235/45 R17 92V tyres.

Figure 10-1 illustrates the wheel and wheel

cover/cap for Executive and Fleet pack models.

Figure 10-1

Techline

Figure 10-2 illustrates the wheel and wheel cover

fitted to Acclaim models.

Figure 10-2

Figure 10-3 illustrates the Berlina road wheel and

cover.

Figure 10-3

Figure 10-4 illus trates the Calais m odel alloy wheel

and cover.

Figure 10-4

Figure 10-5 illustrates the alloy wheel and wheel

cap fitted to the ‘S’ pac k , m odel vehic le. T his wheel

was previously fitted to VS Series, ‘SS’ pack

vehicles.

Figure 10-5

Fig. 10-6 illustrates the alloy wheel fitted to ‘SS’

pack, VT vehicles.

Figure 10-6

Wheel and tyre sizes, inflation pressures and load

capacity are specified on a tyre placard (1) located

on the end surface of the right-hand front door (2),

as shown.

Correct sizes and pressures are the subject of an

Australian Design Rule (ADR) and must be

observed at all times.

Figure 10-7

All models are equipped with a spare wheel/tyre

assembly and tools necessary for a wheel change,

refer Figure 10-8 and Figure 10-9.

SEDAN SPARE WHEEL AND JACK STOWAGE

1 Jack 3 Stowage Compartment

2 Jack/Wheel Nut Wrench 4 Spare Wheel Retaining Stud and Plate

Figure 10-8 Sedan Spare Wheel and Jack Stowage

STATION WAGON SPARE WHEEL AND JACK STOWAGE

1 Jack 3 Stowage Compartment

2 Jack/Wheel Nut Wrench 4 Spare Wheel Retaining Stud and Plate

Figure 10-9 Station Wagon Spare Wheel and Jack Stowage

2. SERVICE OPERATIONS

2.1 REPLACEMENT OF WHEELS AND TYRES

Wheels must be replaced if they are bent, dented

or have excessive lateral or radial run-out. W heels

with greater than specified run-out may cause

objectionable vibration through the vehicle.

Replacement wheels must be equivalent to the

original equipment wheels in load capacity,

diameter, rim width, profile, offset and mounting

configur ation. A wheel of incor rect s ize or type m ay

affect wheel and bearing life, brake cooling,

speedometer/odometer calibration, vehicle to

ground clearance or tyre to body or chassis

clearance.

The s election of replacem ent tyres r equires caref ul

consideration if vehicle handling, braking, steering

response and ride comfort are to be preserved.

In the course of vehicle development, all of the

factors influencing handling and ride comfort are

considered and particular emphasis is placed on

the role of tyres in order to achieve optimum

standards in vehicle performance.

W hen selecting replacement tyres, consult the tyre

placard to determine appropriate tyre sizes. It is

essential that replacements be of the same size,

type and speed/load rating in order to maintain

intended ride, handling and braking. This also

ensures compatibility of new tyres with existing

tyres and the spare tyre.

NOTE:

Do not mix different types of tyres on the same

vehicle except in emergencies, because vehicle

handling may be seriously affected and may result

in loss of control.

It is recommended that new tyres be installed in

pairs on the same axle. If necessary to replace only

one tyre, it should be paired with the tyre having the

most tread, to equalise braking traction.

TYRE MARKINGS

The tyre sidewall has a coded marking system

which gives various information about the tyre.

NOTE:

The effective load capacity for the rear tyres fitted

to VT Series , is 95% of specif ied load capacity due

to the effect of the rear suspension negative

camber.

Tyre Marking Example:

P 205 65 R 15 92 H

P= Passenger Tyre Type

205 = Section Width (‘1’) - mm (‘205’ mm)

65 = Aspect Ratio % (Section Height ‘2’ to

Section Width (‘1’) (‘65’ = 65%)

R= Tyre Construction (‘R’ - Radial)

15 = Rim Diameter - inches (‘15’ = 15”)

92 = Load Index - kg (‘92’ = 630 kg max. load)

(‘94’ = 670 kg max. load)

(‘95’ = 690 kg max. load)

H= Speed Rating (‘H’ = 210 km/h)

(‘V’ = 240 km/h)

Figure 10-10

2.2 TYRE INFLATION AND INSPECTION

The pressure recommended for any model is carefully calculated to give satisfactory ride, stability, steering, tread

wear, tyre life and resistance to wheel/tyre damage.

Tyre pressures, with COLD tyres (after vehicle has stood for three hours or more, or driven less than 2 kilometres)

should be checked weekly or before any extended trip, and set to the specifications on the tyre placard located on

the end surface of the right-hand front door, as shown in Figure 10-7.

When checking tyre pressure, visually inspect tyres for excessive wear, sharp objects embedded in the tyre or

damage to sidewalls.

NOTE 1:

Clean valve exterior, prior to apply ing air pressure nozzle when inflating tyre.

NOTE 2:

Always reinstall valve caps to keep out dust and water.

PRESSURE ADJUSTMENTS TO SUIT OPERATING CONDITIONS

For continuous high speed operation, increase pressures as recommended on the tyre placard.

Tyre pressure can increase as much as 40 kPa when hot. DO NOT REDUCE PRESSURES TO OFFSET THIS

BUILD UP.

For operation on unsealed rough roads, increase COLD tyre pressures 28 kPa above that shown on the tyre

placard.

NOTE:

Tyre pressures are not to be increased for unsealed rough road condition if tyre pressures have already been

increased for high speed operation.

2.3 WHEEL REMOVAL AND INSTALLATION

IMPORTANT:

Before removing any wheel, mark the relationship

of the wheel to the mounting flange or brake

disc/hub.

Difficulty in wheel removal can be caused by either

corrosion or a tight fit between the wheel centre

and the mounting or brake disc/hub flange.

NOTE:

If tightness is caused by corrosion, do not use heat

or heavy impact.

If a wheel is tight, proceed as follows;

1. Tighten and loosen each road wheel attaching

nut a maximum of two turns.

2. Lower vehicle to ground and allow weight of

the vehicle to rest on the wheel.

3. Drive the vehicle approximately 2 metres in a

forward and reverse direction. Apply quick,

hard jabs on the brake pedal to loosen the

wheel.

4. Raise the vehicle and remove road wheel

attaching nuts and remove wheel.

Should a removed road wheel show signs of

corrosion, then all deposits should be removed

from the hub spigot and mating bore of the alloy

wheel, using fine emery paper.

Wash down with mineral spirit, dry and apply a light

coating of a lubricant such as Omega 929 or

equivalent to the hub spigot, using a small brush.

Remove any excess with mineral spirit and allow

the product to dry before installing the road wheel.

NOTE:

Installing wheels without good metal to metal

contact at the mounting surfaces can result in

wheel nuts coming loose. Wheel nuts must be

carefully tightened to the correct torque

specification and in the order shown.

ROAD WHEEL ATTACHING NUT 110 - 140

TORQUE SPECIFICATION Nm

Figure 10-11

2.4 TYRE ROTATION

For VT Series Models, it is recommended that tyre

rotation be carried out when brake inspections are

performed, as per the service schedule outlined in

the VT Owner's Handbook, or when:

1. Difference in tread depth between front and

rear tyres is 1.5 mm.

2. When any unusual tyre wear pattern develops.

If uneven tyre wear is evident, the reason for it

should be corrected if at all possible.

If the tyres are rotated, it is rec omm ended that the

tyre and wheel assembly balance be checked at

the same time, refer to 2.8 WHEEL AND TYRE

BALANCING in this Section.

Tyre rotation in accordance with Fig. 10-12 will

assist in obtaining maximum tyre life.

Figure 10-12

2.5 CHECKING TYRE/WHEEL ASSEMBLY RUN-OUT

Because the run-out of a tyre/wheel assembly will

directly affect the amount of imbalance and radial

force variation, it should be corrected first. The

smaller the amount of run-out, the less imbalance

and force variation. Radial and lateral run-out can

be corrected at the same time. There are two

methods to measure run-out of the tyre/wheel

assemblies:

•On the vehicle (mounted to the hub - wheel

bearing must be in good condition)

•Off the vehicle (mounted on a spin-type

wheel balancer).

NOTE:

Initial on-car inspection should be made prior to off-

car run-out checks.

Measuring the tyre/wheel run-out off the vehicle is

easiest. It is usually easier to m ount a dial indic ator

in the correct location, and the chances of water,

dirt, or slush getting on the dial indicator are

decreased. Once the run-out has been measured

and corrected off the vehicle, a quick visual check

of run-out on the vehicle will indicate if any further

problems exist.

If there is a large difference in the run-out

measurements from on-vehicle to off-vehicle, then

the run-out problem is due to either stud pattern

run-out, hub flange run-out, or a m ounting problem

between the wheel and the vehicle.

Before measuring or attempting to correct

excessive run-out, carefully check the tyre for

an unev en b ead seat . T he distanc e fr om the edge

of the ring to the conc entr ic r im loc ating r ing s hould

be equal around the entire circumference. If the

beads are not seated properly, the tyre should be

remounted. Otherwise, excessive run-out and

imbalance will result.

Important:

If the vehicle has been sitting in one place for a

long time, flat spots may exist at the point where

the tyres were resting on the ground. These flat

spots will aff ect the run-out readings and should be

eliminated by driving the vehicle long enough to

warm up the tyres prior to conducting any run-out

measurements.

PROCEDURE

1. Lift the vehicle on a hoist or suppor t with jack -

stands.

2. In order to get an initial indication of how much

run-out exists, spin each tyre and wheel on the

vehicle by hand (or at a slow speed using the

engine to run the drive wheels). Vis ually check

the amount of run-out from the front or rear.

3. Mark the location of each tyre/wheel assembly

in relation to the wheel studs and to their

position on the vehicle (right front, left rear,

etc.) for future reference.

4. Remove tyre/wheel assemblies one at a time

and mount on a spin-type wheel balancer.

5. Measure the tyre/wheel assembly radial and

lateral run-outs, using a dial indicator fitted

with a roller.

NOTE 1:

With tyres that use an aggressive tread pattern, it

will be necessary to wrap the outer circumference

with tape (as indicated) when measuring radial run-

out, to provide a smooth surface for a more

accurate measurement.

NOTE 2:

Lateral run-out should be measured on a smooth

area of the sidewall, as close to the tread as

possible. Any jumps or dips due to sidewall splices

should be ignored and an average amount of run-

out attained.

1. Slowly rotate the assembly one complete

revolution and zero the dial indicator on the

low spot.

2. Rotate the assembly one more complete

revolution and note the total amount of run-out

indicated.

As a guide, the tyre/wheel assembly, radial and

lateral run-out should be no more than 1.5 mm

when measured off the vehicle.

Figure 10-13

MATCH MOUNTING

NOTE:

W hile this operation is not norm ally necessary with

original equipment tyres, when replaced, match

mounting is recommended to obtain optimum

vehicle handling and performance.

If tyre/wheel assembly run-out is excessive, mark

the location of the high and low spot on the tyre

and the wheel. The next st ep will be to deter m ine if

the run-out problem exists in the tyre, wheel, or a

combination of both, then to correct it. The

procedure us ed to accom plish this is called m atch-

mounting or system matching.

1. Place a mark on the tyre sidewall (1) at the

location of the valve stem (3). This will be

referred to as the 12:00 o’clock position. The

location of the high spot (A) will always be

referred to in relation to its clock position on

the wheel.

2. Mount the tyre wheel assembly on a tyre

machine and break down the bead. Do not

dismount the tyre from the wheel at this time.

3. Rotate the tyre 180° on the rim so the valve

stem referenc e m ark (2) is now at 6:00 o’clock

in relation to the valve stem itself. Inflate the

tyre and make sure the bead is seated

properly. You may have to lube the bead to

easily rotate the tyre on the wheel.

4. Install the assembly on the tyre balancer and

again measure the run-out. Mark the new

location of the run-out high point (B) on the

tyre.

If the run-out is now within tolerance, no further

steps are necessary. The tyre may be balanced

and installed on the vehicle.

Alternatively, if the clock location of the high spot

(B) remained at or near the clock location of the

original high spot (A) (as in Figure 10-14), the

wheel is the major contributor to the run-out

problem. It should be measured for excessive run-

out, as detailed in 2.6 CHECKING WHEEL RUN-

OUT and replaced if found to exceed specification.

If the high spot is now at or near a position 180°

(6.00 o’clock ) f rom the or iginal high spot, the tyre is

the major contributor (as in Figure 10-15) and

should be replaced.

Always remeas ure the tyr e/wheel as sembly run-out

after replacing the tyre and make sure the run-out

is within tolerance befor e continuing. In the m ajority

of cases, the first 180° rotation of the tyre will either

correct the run-out problem or indicate which

component to replace.

If the high spot is between the two extremes, then

both the tyre and wheel are contributing to the run-

out. Try rotating the tyre an additional 90° in both

the clockwise (9.00 o’clock) and anti-clockwise (3

o’clock) directions, measuring the run-out after

each rotation.

Figure 10-14 Wheel is the Major Contributing Factor

Figure 10-15 Tyre is the Major Contributing Factor

If run-out cannot be corrected by match-mounting,

then the tyre must be removed and the wheel run-

out measured, as detailed in the next Operation.

Once run-out has been brought within the

tolerance, the tyre/wheel assembly should be

balanced.

2.6 CHECKING WHEEL RUN-OUT

Wheel run -out should be measured on the inside

bead area of the wheel. Measure the run -out in the

same fashion as tyre run-out. Ignore any jumps or

dips due to paint drips, chips, or welds, measure

both inboard and outboard.

If the run-out of the wheel is within tolerance, and

the tyre/wheel assembly run -out cannot be reduced

to an acceptable level by using the match-mounting

technique, the tyre must be replaced. Always

measure assembly run

-out after replacing the

tyre.

If there is a large difference in the run-out

measurements from on-vehicle to off -vehicle, then

the run-out problem is due to either stud pattern

run-out, hub flange run-out, or a mounting problem

between the wheel and the vehicle.

The tolerances listed are to serve as guidelines.

If run-out measurements are within tolerance but

are marginal, some sensitive vehicles may still be

affected. It is always advisable to reduce run -out to

as little as possible in order to attain optimum

results under all conditions.

PROCEDURE

NOTE:

This measuring procedure can be used equally well

on either steel or alloy road wheels.

1. Raise vehicle and support on safety stands.

2. Remove wheel cover (steel wheels) or centre

cap (alloy wheels).

3. Mark relationship of wheel to mounting flange

or brake disc/hub. Remove wheel attaching

nuts and remove wheel.

4. Mark relationship of tyre to wheel rim and then

remove tyre from rim.

5. Check that the wheel and mounting flange or

brake disc/hub mating surfaces are clean and

free from burrs etc.

6. Install the wheel onto the mounting flange or

brake disc/hub and install wheel attaching

nuts. Tighten nuts to the correct torque

specification.

ROAD WHEEL ATTACHING NUT 110 - 140

TORQUE SPECIFICATION Nm

7. Using a dial indicator with a roller fitted to the

probe, secure the base to a fixed point. Then,

slowly rotate the road wheel and measure

wheel run-out at the points shown.

1 = Lateral Run-out.

2 = Radial Run-out.

Wheel run-out should be within the specified

values listed in 4. SPECIFICATIONS in this

Section.

If not within specification, replace wheel.

NOTE:

Always measure the run-out of new wheels when

replacing old ones. Do not assume that a new

wheel is automatically a known good component.

Figure 10-16

2.7 TYRE REMOVAL AND INSTALLATION

Whenever possible, tyre rem oval and installation s hould be carried out on a tyre changing m achine. T he use of tyre

levers and mallets is likely to damage tyre carcasses and wheel rims.

Minor dents and burr s on steel rim s can be r epaired by f iling, but alloy rim s m ust always be r eplaced if significantly

damaged.

CAUTION:

Wheels must not be welded, brazed, peened or treated in any manner which could weaken them.

The bead seat of the rim must be clean and smooth; rust, rubber etc. may be removed with a wire brush or steel

wool.

Before r emoving or ins talling a tyre, or installing a valve stem , apply tyre lubricant (Holden's Specific ation HN1162)

to the tyre bead and rim flanges.

Install valve stem and tyre before lubricant dries.

Initially, inflate tyre to 280 kPa to ensure that the tyre beads seat correctly in the rim flanges.

If the tyre beads fail to seal at this pressure, def late the tyre, lubric ate the tyr e beads and wheel rim again and then

inflate.

WARNING:

Exercise care to avoid personal injury when the tyre bead snaps over the wheel rim safety humps.

NOTE:

When fitting a tyre to a rim, it is important to ensure that the tyre is correctly indexed to the rim, i.e. the first

harmonic high point of the tyre should be fitted so that it is matching the first harmonic low point of the rim. This

matching minimises force variations inherent with tyre and rim manufacture. (Refer to 3. DIAGNOSIS in this

Section for more information on harmonics.)

As different origins of tyres have different standards regarding the first harmonic point, refer to the following as a

guide to the correct ty re fitting position.

Australian manufactured tyres have a red dot indicating the first harmonic high point.

European manufactured tyres have a white dot indicating the first harmonic low point.

Some J apanese m anuf actured tyres have a red dot indicating the f irst har m onic high point and a yellow dot (which

should be ignored) which indicates a static balance point.

As independent rear suspension vehicles are more sensitive to a wheel/tyre imbalance condition than other

suspension designs, particular care should be given to correct fitment of tyres to all VT vehicles.

AUSTRALIAN MFD. TYRES

(Red dot on s/wall)

Align RED dot on tyre to mark on outer

flange of wheel, or if there is no mark on the wheel,

align RED dot to low spot of wheel as measured

with dial indicator.

EUROPEAN MFD. TYRES

(White dot on s/wall)

Align WHITE dot on tyre 180° from the mark on

outer flange of wheel, or if there is no mark on the

wheel, align WHITE dot 180° from the low spot of

wheel as measured with dial indicator.

JAPANESE MFD. TYRES

If there is a YELLOW dot but not a red dot use the

rule for Australian tyres. If there is a YELLOW and a

RED dot, ignore the yellow dot and use the red dot

as per rule for Australian tyres.

TYRE REPAIRS

There are many different materials and techniques available to repair tyres. It is suggested that details of materials

and procedures for the repair of tyres should be obtained from the tyre manufacturer.

2.8 W HE EL AND TYRE BALANCING

There are two types of wheel and tyre balance;

Static and Dynamic.

STATIC balance is the equal distribution of weight

around the wheel.

Vibrations caused by static imbalance will cause a

vertical or bouncing motion of the tyre.

Figure 10-17

DYNAMIC balance aff ects the distr ibution of weight

on each side of the tyre/wheel centreline.

Dynam ic imbalanc e results in a side-to-side m otion

of the tyre, sometimes referred to as shimmy.

Figure 10-18

OFF-VEHICLE BALANCING

When wheel and tyre assemblies require

balancing, they should be removed from the

vehicle and balanced on a machine capable of

ensuring correct static and dynamic balance.

Balancing should be car ried out in accordanc e with

the machine manufacturer's instructions to obtain

the results as outlined under BALANCE LIMITS.

Although hub/brake discs do not contribute

significantly to an out of balance condition, it is

desirable to fit wheels to the same position on the

vehicle after balancing. Accordingly, it is good

practice to mar k the r elations hip of the wheel to the

axle flange or brake hub/disc, prior to wheel

removal.

Before balancing, remove all accumulated mud

from the wheel and any embedded stones f rom the

tyre treads. If using on-vehicle balancing

equipment, observe the LIMITED SLIP

DIFFERENTIAL PRECAUTIONS as outlined in

Section 4B FINAL DRIVE AND DRIVE SHAFTS.

ON-VEHICLE BALANCING

If checking and/or correcting a tyre/wheel

imbalance condition off the vehicle and it is not

possible or does not corr ect the vibration, it m ay be

necessary to balance the assembly/ies while

mounted on the vehicle, using an on-vehicle, high-

speed spin balancer. This will balance the hubs,

rotors, and wheel trim s sim ultaneously. Also, it can

compensate for any amount of residual run-out

encountered as a r esult of m ounting the tyre/wheel

assembly on the vehicle, as opposed to the

balance that was achieved on the off-vehicle

balance.

Always follow the on-vehicle balancer manuf ac ture r

Operator's Manual for specific instructions.

NOTE 1:

Do not remove the off-vehicle balance weights.

The purpose of on-vehicle balance is to "fine tune"

the assembly balance already achieved, not to

begin again.

NOTE 2:

Leave all wheel trims installed where possible.

Some wire wheel covers have been known to

induce static imbalance. If you suspect a wheel trim

of causing the vibration, it can be eliminated by

road testing the vehicle with the wheel trim

removed.

NOTE 3:

If the on-vehicle balance calls for more than 10

grams of additional weight, split the weight between

the inboard and outboard flanges of the wheel, to

avoid disturbing the dynamic balance of the

assembly, achieved in the off-vehicle balance

procedure.

NOTE 4:

Evaluate the condition following the on-vehicle

balance to determine if the vibration has been

eliminated.

BALANCE LIMITS

Maximum allowable out of balance is 8 grams per

side of rim. Total balance weights are not to exceed

120 grams per wheel with a max imum of 80 gram s

per wheel flange. If a wheel assembly requires

more than these limits, fit another tyre to the wheel

and re-balance.

NOTE:

Specific wheel weights for each design of wheel are

used. This is due to the differences in wheel rim

profile.

Figure 10-19

2.9 WHE EL ATTACHING NUTS/STUDS

Important:

W hen alloy wheels are fitted to VT series vehicles,

special attaching wheel nuts (2) are also used. If

VT alloy wheels are to be fitted to a vehicle

normally equipped with steel wheels, then the

original nuts (1) MUST be discarded and revised

design attaching nuts used on the replacement

wheels.

For removal and installation instructions for the

wheel attaching studs (3), either refer to

Section 3 FRONT SUSPENSION or

Section 4B FINAL DRIVE AND DRIVE SHAFTS.

All models use metric (M12 x 1.5) wheel attaching

studs and nuts (refer to A, in Figure 10-20). Figure 10-20

Techline

3. DIAGNOSIS

3.1 WEAR

Analysis of tyre wear conditions is adequately

covered in tyre company literature.

3.2 ROAD TESTING

Because there are many reasons for a vibration condition to be present in a vehicle, it is vital that a thorough road

test be conducted, to eliminate other possible causes for a vibration condition being present.

TYRE AND WHEEL INSPECTION

This visual inspection should be conducted for all vibration complaints unless the disturbance only occurs with the

vehicle at a standstill.

The tyres should be inspected for unusual wear, including cupping, flat spots and heel-and-toe wear. These

conditions can cause tyre growl, howl, slapping noises, and vibrations throughout the vehicle.

Establish that all tyres are inflated to the correct pressures prior to any road test.

Check for bulge’s in the sidewalls.

Check all wheels for bent rim flanges. Many times, hub caps or trim rings that appear dented, can indicate a bent

wheel underneath.

SLOW ACCELERATION TEST

This test is to identify engine or vehicle speed related conditions. It will be necessary to perform additional tests in

order to determine in which category the vibration belongs.

1. On a smooth, level road, slowly accelerate up to highway speed.

2. Look for disturbances that match the customer's description.

3. Note the vehicle speed (km/h) and engine speed (rpm) where the disturbance occurs.

Follow this test with the neutral coast-down test, and the downshift test.

NEUTRAL COAST-DOWN TEST

1. On a smooth, level road, accelerate to a speed slightly higher than the speed at which the vibration occurs.

2. Shift the vehicle into NEUTRAL and coast down through the vibration range. Note if the vibration is present in

NEUTRAL.

If the vibration still occurs in NEUTRAL, it is definitely vehicle-speed sensitive. At this point, the engine and

torque converter have been eliminated as a cause. Depending on the symptoms or frequency, the repair will

concentrate on either the tyres and wheels or the propshaft and rear axle.

DOWNSHIFT TEST

1. On a smooth, level road, accelerate to the speed at which the complaint vibration occurs. Note the engine rpm.

2. Next, decelerate and safely downshift to the next lower gear (from overdrive to drive, or from drive to second,

etc.).

3. Operate the vehicle at the previous engine rpm.

If the vibration returns at the same rpm, the engine or torque converter are the most probable causes. To

confirm these results, repeat this test in still lower gears, and in NEUTRAL.

STEERING INPUT TEST

This test is intended to determine how much wheel bearings and other suspension components contribute to a

vibration, especially those relating to noises, howl or growl, grinding and roaring.

With the vehicle at the vibration speed (km/h), drive through slow, sweeping turns - first in one direction, then the

other.

If the vibration is either worse or goes away, the wheel bearings, hubs, tyre tread wear (etc.) are all possible causes.

STANDING START ACCELERATION

The purpose of this test is to duplicate a vibration called “Take Off Shudder”. In some cases, a powertrain mount or

the exhaust contacting the body may also be suspect, depending on the symptoms.

1. With the vehicle at a complete stop and in gear, remove your foot from the brake.

2. Accelerate to 60 or 70 km/h while checking for vibrations that match the customer's description.

Shudder in the seat or steering wheel under these conditions usually results from improper driveline angles. Worn,

tight or failed universal joints may also be a cause, and should be inspected first.

Grunting or groaning noises along with a buzzing or roughness in the floor usually points to the vibration being

conducted through the engine or transmission mounts, or through exhaust mounts and hangers that have

“GROUNDED OUT”. Refer to the respective Sections for rectification procedures.

3.3 VIBRATION

To determine the cause of a vibration condition that is suspected of being tyre/wheel related, a key aspect is to

understand the nature of first and second order vibrations (or harmonics).

As shown in Figure 10-21, a tyre with one high spot would create a disturbance once every complete revolution.

This is called first-order.

An oval shaped tyre with two high spots would create a disturbance twice per revolution. This is called second-

order.

Three high spots would be third order, and so on.

Two first-order vibrations m ay add to or subtract from the overall amplitude of the disturbance, but that is all. Two

first-order vibrations do not equal a second-order. Due to centrifugal force, an imbalanced component (tyres,

propshafts, engine) will always create a first-order vibration.

Figure 10-21

If wheel and tyre assemblies are balanced to the degree required and vibration is still evident, then tyre run-out or

‘Force Variation' could be responsible.

RADIAL FORCE VARIATION

Radial force variation refers to a difference in the

stiff nes s of a tyre sidewall as it rotates and contacts

the road. Tyre/wheel assem blies have som e of this

due to splices in the different plies of the tyre, but

they do not cause a problem unless the force

variation is excessive. These stiff spots in the

sidewall can deflect the tyre/wheel assembly

upward as they contact the road.

If there is only one stiff spot in the sidewall, it will

deflect the spindle once per each revolution of the

tyre/wheel assembly, causing a first order

tyre/wheel vibration.

If there are two stif f spots , they can cause a sec ond

order vibration.

First and second order tyre/wheel vibrations are the

most common to occur as a result of radial force

variation. Higher orders (third, fourth, etc.) are

possible, but quite rare. The most effective way to

minimise the possibility of force variation as a factor

in tyre/wheel vibration is to ensure that the

tyre/wheel assembly run-out is at an absolute

minimum.

Some tyre/wheel assemblies may exhibit vibration

causing amounts of force variation even though

they are within run-out and balance tolerances. Due

to tighter tolerances and higher standards in

manuf acturing, these instances are becom ing rare.

If force variation is suspected as being a factor,

substitute one or more known good tyre/wheel

assemblies for the suspect assemblies. If this

rectifies the problem replace the offending tyre.

Figure 10-22

LATERAL FORCE VARIATION

This is based on the same concept as radial force

variation, except that later al forc e variation tends to

deflect the vehicle sideways or laterally, as the

name implies. It can be caused by a ‘snaky’ belt

inside the tyre. Tyre replacement using the

substitution method may be necessary.

This condition is very rare and again, the best way

to eliminate it as a factor is to ensure that the

lateral run-out of the tyre/wheel assemblies is at an

absolute minimum.

In most cases where excessive lateral force

variation exists, the vehicle will display a ‘wobble’ or

‘waddle’ at low speeds (8 to 40 km /h) on a s mooth

road surface. The condition will usually be related

to a first order vibration of ty re/wheel rotation.

Tyre run-out will always be pr esent to som e degr ee

due to dimensional tolerances in both the tyre and

wheel and can often be r educ ed by rotating the tyre

on the wheel to cancel out the overall effect. The

same problem can be caused by ‘Force Variation'

which is, in effect, a variation in stiffness around

the tyre which res ults in a varying loaded radius as

the tyre rotates.

All of these factors have so far been considered to

act radially. However lateral run-out and lateral

force variation can also be translated into vehicle

vibration ranging from low speed ‘waddle' to

relatively high speed shake or vibrations similar to

those obtained with tyre imbalance. The following

diagnosis procedure indicates the process of test

and logic required to deter mine the cause of wheel

and tyre induced vibration.

3.4 LEAD

‘Lead' is the deviation of the vehicle from a straight path on a level road (no camber) with no load on the steering

wheel and is usually caused by alignment, brake drag etc., but can sometimes be caused by tyres.

The way in which a tyre is built can produc e lead in a vehicle. An exam ple of this is placem ent of the belt in a r adial

tyre. Off centre belts can cause the tyre to develop a side force while rolling straight down the road.

If one side of the tyre is a little larger in diameter than the other, the tyre will tend ‘to roll up' to one side. This will

develop a side force which can produce vehicle lead. Before attempting to find a faulty tyre, wheel alignment,

brakes, steering components etc., should be thoroughly checked.

The following diagnostic chart can be used to confirm vehicle lead.

DIAGNOSING VEHICLE LEAD

STEP ACTION YES NO

1Inflate tyres to the correct pressures.

Road test vehicle in opposite directions, on a level,

uncrowned road with no wind.

Does vehicle ‘lead’ to the same side in both directions?

Go to Step 2. Go to Step 8.

2Swap front tyres from one side to the other and road test,

again in opposite directions.

Does vehicle ‘lead’ to the same side as in Step 1?

Put tyres back in

original positions.

Go to Step 8.

Go to Step 3.

3Does the vehicle now lead to the opposite side to that in

Step 1? Go to Step 5. Go to Step 4.

4Has the lead condition been corrected? Leave tyres as is. If

roughness develops,

replace front tyres.

Go to Step 5.

5Install a known good tyre to replace one front tyre and road

test again.

Is the lead condition corrected?

Lead condition has

been isolated.

Replace tyre.

Go to Step 6.

6Check test tyre on a known good vehicle.

Has the lead condition been corrected?

Test tyre is faulty -

replace.

Go to Step 5.

Go to Step 7.

7Install a known good tyre to replace remaining front tyre.

Has the lead condition been corrected?

Lead condition has

been isolated.

Replace tyre.

Go to Step 8.

8Check/correct vehicle wheel alignment and mal-adjusted or

binding steering.

Road test again. Has the lead condition been corrected?

Vehicle is now

operating to

specification.

Swap tyres, front

to rear.

Go to Step 4.

4. SPECIFICATIONS

STEEL WHEEL

Rim Width Code 6.0J

Diameter Code 15

Maximum Permissible Radial Run-out 0.6 mm

Maximum Permissible Lateral Run-out 0.8 mm

Offset 43 mm (positive)

ALLOY WHEELS

Rim Width Code 6.0J 7.0J 8.0J

Diameter Code 15 16 17

Maximum Permissible Radial Run-out

Berlina 0.25 mm

‘S’ 0.25 mm

‘SS’ 0.25 mm

Calais 0.25 mm

Maximum Permissible Lateral Run-out

All models 0.3 mm

OffsetBerlina 43 mm (pos)

‘S’ 43 mm (pos)

‘SS’ 48 mm (pos)

Calais 48 mm (pos)

TYRES

Dynamic Balancing - All

Maximum Permissible Wheel/Tyre Out of Balance 150 g

Maximum Permissible Tyre Radial

1st Harmonic Force Variation (tyre only) 65 N

Maximum Load Rating (per tyre) *

92H 630 kg

Refer to 2. SERVICE OPERATIONS - TYRE MARKINGS, in this Section.

RECOMMENDED COLD INFLATION

kPa

MODEL WHEEL TYRE

DESIGNATION Up to 3

Passengers Up to

Maximum Load

Front Rear Front Rear

Executive 6.0J x 15

Steel P205/65

R15 92H 200 200 240

270 (1) 240

300 (1)

Berlina 6.0J x 15

Alloy P205/65

R15 92H 200 200 240

270 (1) 240

300 (1)

S 7.0J x 16

Alloy P225/50

R16 92V 200 200 240

270 (1) 240

310 (1)

SS 8.0J x 17 P235/45

R17 92V 200 200 240

270 (1) 240

310 (1)

Calais 7.0J x 16

Alloy P215/60

R16 92H 180 180 240

240 (1) 250

280 (1)

(1) Where vehicle is used for consistent speed in excess of 140 km/h,

required cold inflation pressures are to be as indicated.

5. TORQUE WRENCH SPECIFI CATIONS

ROAD WHEEL ATTACHING NUTS Nm

Steel Wheel 110-140

Alloy Wheel 110-140