Tire Runout

ALIGNMENT CONCERNS
Verify that tires are matched from side to side, equally inflated, and uniformly worn. Also, look for abnormal tread wear patterns indicating wheel/tire imbalance or suspension misalignment. If cupping or flat spots are present, wheels and tires should be checked for runout and balance.

If tread wear is not uniform across the face of the tire, but greater toward the inboard or outboard edges improper camber is indicated. This can be verified by an alignment check.

Tread wear in a saw-tooth pattern, which can be felt even if not visible, results from improper toe adjustment. If the high edges of the tread ribs are toward the vehicle center, excessive toe-in is indicated. If the high edge is away from the vehicle center, toe-out is excessive. If necessary, adjust toe to proper specifications.





TREAD WEAR INDICATORS
The tires should be replaced if the wear indicators are exposed, or if there is severe shoulder wear. Shoulder wear is usually caused by excessive camber or excessive toe on radial tires.





CUPPING OR SCALLOPING
Sometimes bad spring and shock assemblies will cause severe cupping or scalloped tire wear on non-drive wheels.

If the cupping or other wear patterns are severe enough to cause noise or vibration, the tire must be replaced. Tire rotation at proper intervals will prevent these tire patterns from developing.





CENTER TREAD WEAR
Radial tire center tread wear can be caused by overinflation, heavy acceleration or excessive toe on drive wheels.





TREAD DISTORTION
A nail puncture may allow water to seep in and rust out one of the steel belts in a radial tire. Internal stresses in the tire caused by the loss of one of the steel belts will cause the tread to distort. Tread distortion is often incorrectly referred to as belt shift.

This condition will cause low speed waddle and vibration similar to a statically unbalanced tire at high speed. A tire with severe tread distortion should be replaced.