Tire wear and vibration diagnostics

Tire wear diagnostics

New tires should be installed when wear indicators are exposed or if there is severe wear on the tire shoulder. Shoulder wear is usually caused by increased camber or toe-in.

In some cases, improperly adjusted rear wheel alignment or strut wear will result in pronounced "cup-shaped" or "funnel-shaped" wear on the non-driven wheels.

Severe rear wheel alignment also causes other unusual wear patterns to appear.

Tire vibration diagnostics

The tire vibration diagnostic procedure always begins with a road test. For more information, refer to Section 100-04. The road test and customer interview (if possible) will provide much of the information needed to determine the cause of the vibration.

When performing a road test, the vehicle should be driven on a smooth, uneven road. If vibration is evident, note and record the following:

• the speed at which vibration occurs.
• the type of vibration that occurs in each speed range: mechanical or sound vibration.
• how does changing engine torque affect vibration?; car speed; engine crankshaft speed.
• vibration type - sensitivity: torque sensitive, vehicle speed sensitive or engine speed sensitive.

The following explanations will help you determine the source of the vibration.