Glossary of Terms

1. WHEEL AND TIRE RUNOUT








Runout is a measurement of the eccentricity of the wheel and tire with respect to the spindle. Lateral runout is measured in the axial direction parallel to the spindle. The radial runout is measured in the vertical direction perpendicular to the spindle. Figures 1, 2 and 3 show the runout measurement directions and location of measurements.

2. STATIC ONE-PLANE OFF CAR BALANCER:





The simplest and least expensive type of wheel balancer is the off-the-car static type or "bubble balancers" (see Figure 4).

3. TWO-PLANE OFF CAR BALANCER:





Figure 5 shows a typical two-plane off car balancer. This balancer corrects the wheel and tire assembly balance dynamically in both the radial (vertical) and lateral (axial) planes.

4. STATIC BALANCE:





Static balance is the equal distribution of weight around the wheel (see Figure 6). Wheels that are statically unbalanced may cause a bouncing action called tramp (see Figure 7).

5. DYNAMIC BALANCE:





Dynamic balance is the equal distribution of weight on each side of the centerline so that when the tire spins there is no tendency for the assembly to move side-to-side (see Figure 8). Wheels that are dynamically unbalanced may cause wheel shimmy (see Figure 9.).