Wheels and Tires: Testing and Inspection

VIBRATION DIAGNOSIS
Wheel unbalance causes most of the highway speed vibration problems. If a vibration remains after dynamic balancing, it can be caused by three things.
1. Tire runout.
2. Wheel runout.
3. Tire stiffness variation.
Measuring tire and/or wheel free runout will uncover only part of the problem. All three causes, known as loaded radial runout, must be checked by using a Tire Problem Detector (TPD). If a TPD is not available, the more time consuming method of substituting known good tire and wheel assemblies on the problem vehicle can be used.