What is runout in the context of wheels and tires?

Runout, in the context of wheels and tires, refers specifically to the up-and-down or side-to-side movement of the wheel or tire as it rotates. This movement can be described as variations or deviations from the true circular motion of the wheel or tire, which can result in uneven tire wear, vibrations, and handling issues while driving.

When wheels are mounted on the vehicle, they should ideally rotate in a perfect circle. However, factors like manufacturing tolerances, imperfections in the rim or tire, and installation errors can cause the wheel or tire to wobble slightly, leading to runout. This condition can be measured in terms of radial runout (vertical movement) or lateral runout (side-to-side movement).

Understanding runout is crucial for proper vehicle alignment and overall ride quality. Significant runout can indicate issues with the wheel or tire, necessitating inspection and potential corrective action, such as balancing the wheel or replacing damaged components.