Component Tests and General Diagnostics

Component Tests
Wheels and Tires
For wheel and tire specification information (pressures, torques, etc).
When replacing wheels or tires, local legislation regarding health and safety must be complied with.
If the vehicle has a Tire Pressure Monitoring System installed, only Jaguar approved wheels and tires should be used. If the wheel and tire size is changed (for example from R18 to R20) the Tire Pressure Monitoring System module should be updated with the correct pressure information appropriate to the new wheel and tire set. Update the Tire Pressure Monitoring System module using the Jaguar approved diagnostic system.
As a general guideline, only replace tires in pairs or as a set, and only with tires of equivalent size and specification.
Confirm the symptoms of the customer complaint.
As much information as possible should be gathered from the driver to assist in diagnosing the cause(s).
1 Before a road test, carry out a basic inspection to make sure the vehicle is safe and legal to drive.

Basic inspection
- Correct tire inflation
- Legal tire tread depth
- Cuts/Bulges in tire sidewall(s)
- Tire ply separation
- Embedded objects
- Wheel rim damage
- Correct tire installation (specification, direction of rotation, etc)
- Any obvious distortion of the tire (flat/high spots)
- Worn/Damaged steering or suspension components
Road test
If the results of the basic inspection are acceptable, carry out a road test to confirm the symptoms.
To reproduce the symptoms, test the vehicle on similar roads to those on which the fault occurs and at similar speeds (provided it is legal to do so).
If the vibration or noise can be reproduced, note the speed at which it occurs and see if it is possible to drive through the symptom, meaning, is it possible to alter the fault by driving faster or slower than the speed at which it occurs?
If it is possible, it is likely that the fault is caused by an imbalance in the wheel or tire.
If the vibration or noise gets worse as the vehicle speed increases, it is likely that the fault is caused by distortion in the wheel or tire, or worn or damaged components.
Distortion checks


Check for distortion by raising the vehicle so that the wheels are free and placing an axle stand or similar fixed object next to each wheel in turn.
If the stand is placed at the tread of the tire, the tire can be checked for ovality by turning the wheel by hand and checking for high or low spots where the gap between the tread and the stand increases or reduces.
If the stand is placed next to the wheel rim or tire sidewall, the wheel and tire can be checked for run-out in a similar way.