Wear Spots
Wear spots are caused by a hard stop with locked wheels whereby the rubber compound is abraded from the contact surface.
When the tires slide across the road surface, frictional heat is generated which reduces the abrasion resistance on the tread compound.
Even the most abrasion resistant tread compound cannot prevent wear spots which can occur during extreme braking.
Even ABS cannot completely prevent brief locking and the resulting slightly flat spots.
The degree of abrasion is primarily dependent on the vehicle speed, road surface and tire load. For clarification see the following examples.
If a vehicle with locked front wheels is decelerated until it comes to a stop on a dry road surface, the rubber abrasion on the post card sized contact patch is approximately:
- from 57 km/h (35.4 mph) = 23.8 m (78.1 feet) braking distance, up to 2.0 mm,
- from 75 km/h (46.6 mph) = 41.8 m (137.1 feet) braking distance, up to 3.3 mm,
- from 92 km/h (57.2 mph) = 71.6 m (234.9 feet) braking distance, up to 4.8 mm.
Wear Spots in Tread
Tires with this type of damage cannot be used and must be replaced.