Tire Noise and Marks

TIRE SKIDDING & MARKS
Although the ABS system prevents complete wheel lock-up, some wheel slip is desired in order to achieve optimum braking performance. During brake pressure modulation, as brake pressure is increased, wheel slip is allowed to reach up to 30%. This means that the wheel rolling velocity is 30% less than that of a free rolling wheel at a given vehicle speed. This slip will result in some tire "chirping", depending on the road surface. This sound should not be interpreted as total wheel lock-up.

Complete wheel lock-up normally leaves black tire marks on dry pavement. However, anti-lock braking will not leave dark black tire marks since the wheel never reaches a locked condition. Tire marks will, however, be noticeable as light patched marks.

Although ABS operation is available at speeds above approximately 12-15 mph, it is automatically turned off at speeds below 3-5 mph. Therefore, wheel lock-up may be perceived at the very end of an anti-lock stop and should be considered normal.