Jaguar XJ (X350). Manual — part 92

WARNING: When using winter tires, observe the direction of the sidewall moulded

indicators; correct tire rotational direction is critical. Failure to follow these instructions may result

in personal injury.

WARNING: A tire and wheel must always be correctly matched. Wider or narrower tires

than recommended could cause danger through sudden deflation. Failure to follow these

instructions may result in personal injury.

WARNING: When using the temporary spare wheel, maximum speed must not exceed 80

km/h (50 mile/h). Drive with caution and replace with the specified wheel and tire assembly as

soon as possible. Failure to follow these instructions may result in personal injury.

WARNING: Traction control (if available) must not be engaged with a temporary spare

wheel fitted. Failure to follow these instructions may result in personal injury.

WARNING: When changing a wheel, make sure that the vehicle cannot move. Always apply

the parking brake and select the transmission park position. Failure to follow these instructions

may result in personal injury.

WARNING: Never run the engine with one wheel off the ground, for example, when

changing the wheel. The wheel resting on the ground may cause the vehicle to move. Failure to

follow these instructions may result in personal injury.

WARNING: Tighten the wheel nuts to specification. Too tight may cause damage, too loose

may allow the wheel to become detached. Failure to follow these instructions may result in
personal injury.

WARNING: Use only wheels and wheel nuts supplied by Jaguar. Aftermarket wheels or

wheel nuts may not fit or function correctly and could cause injury or damage. Failure to follow

these instructions may result in personal injury.

Inspection and Verification

1 . Verify the customer's concern by driving the vehicle.

2 . Visually inspect for obvious signs of damage:

Visual Inspection Chart

Mechanical

Incorrect tire pressure

Wheel imbalance

Tires worn beyond tread wear indicators

Cuts

Abrasions

Bulges (blister)

Ply separation

Embedded objects

Impact damage

Incorrect speed rating

Incorrect load rating

Incorrect rotational direction

1 . If an obvious cause for an observed or reported concern is found, correct the cause (if possible)

before proceeding to the next step.

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2 . If the concern is not visually evident, verify the symptom and refer to Symptom Chart.

Tire Wear Inspection

To maximize tire performance, inspect the tires for signs of incorrect inflation and uneven wear

which may indicate a need for balancing, rotation or front suspension alignment. Tires should also be

checked frequently for cuts, stone bruises, abrasions, blisters, and for objects that may have become

embedded in the tread. More frequent inspections are recommended when rapid or extreme

temperature changes occur or when road surfaces are rough or occasionally littered with debris.

Tire Wear Diagnosis

New tires should be installed if the wear indictors are exposed or if there is severe shoulder wear.

Shoulder wear is usually caused by either excessive camber or excessive toe on radial tires.

Sometimes incorrect rear toe settings or damaged struts will cause severe cupping' or scalloped' tire

wear on non-drive wheels.

Incorrect rear toe alignment will also cause other unusual wear patterns.

Road Test

A tire vibration diagnostic procedure always begins with a road test. The road test and customer

interview (if available) will provide much of the information needed to find the source of a vibration.

During the road test, drive the vehicle on a road that is smooth and free of undulations. If vibration is

apparent, note and record the following:

•

The speed at which the vibration occurs.

•

What type of vibration occurs in each speed range. Mechanical or audible.

•

How the vibration is affected by changes in the following: Engine torque. Vehicle speed.
Engine speed.

•

Type of vibration-sensitivity: torque sensitive, vehicle speed sensitive or engine speed
sensitive.

The following explanations help isolate the source of the vibration.

Torque Sensitive

This means that the condition may be improved or made worse by accelerating, decelerating,

coasting, maintaining a steady vehicle speed or applying engine torque.

Vehicle Speed Sensitive

This means that the vibration always occurs at the same vehicle speed and is not affected by engine

torque, engine speed or the transmission gear selected.

Engine Speed Sensitive

This means that the vibration occurs at varying vehicle speeds when a different transmission gear is

selected. It may sometimes be isolated by increasing or decreasing engine speed with the

transmission in NEUTRAL or by stall testing with the transmission in gear. If the condition is engine

speed sensitive, the cause is probably not related to the tires.

If the road test indicates that there is tire whine, but no shake or vibration, the noise originates with

the contact between the tire and the road surface.

A thumping noise usually means that the tire has a flat or soft spot making a noise as they slap the

roadway. Tire whine may be distinguished from axle noise. Tire whine remains the same over a range

of speeds.

Tires show excess wear on edge of treads

Possible Source(s):

•

Tires under-inflated.

Action(s) to take:

•

Correct pressure to specification.

Possible Source(s):

•

Vehicle overloaded.

Action(s) to take:

•

Correct as required.

Tires show excess wear on edge of treads (having the correct tire

pressures)

Possible Source(s):

•

Incorrect toe setting.

Action(s) to take:

•

Set to specification. For additional information,

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Tires show excess wear in center of tread

Possible Source(s):

•

Tires over-inflated.

Action(s) to take:

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