Vibration Diagnosis

Vibration Diagnosis
Wheel imbalance causes most highway speed vibration problems. A vibration can remain after dynamic balancing because
^ A tire is out of round.
^ A rim is out of round.
^ A tire stiffness variation exists.

Measuring tire and wheel free runout will uncover only part of the problem. All three causes, known as loaded radial runout, must be checked using the method of substituting a known good tire and wheel assembly on the problem vehicle. Low-speed vibrations, which occur below 64 km/h (40 mph), are usually caused by runout. High speed vibrations, which occur above 64 km/h (40 mph), can be caused by either imbalance or runout.