The Effect of Tire Tread Depth on Antilock-Brake System (ABS) Decelerations on Dry and Wet Asphalt and Concrete Road Surfaces

The effect of tire tread depth on the deceleration performance of anti-lock brake systems (ABS) in newer vehicles is not well studied. A single sport-utility vehicle (SUV) was used to perform a series of 216 ABS-engaged braking tests on dry and wet asphalt and concrete surfaces using six sets of four tires with tread depths varying from 0.8 mm (1/32″) to 7.1 mm (9/32″). Vehicle speed and deceleration as a function of time were calculated from 5th-wheel displacement data sampled at 200 Hz. Braking tests were initially conducted on a dry surface, after which a water truck distributed water onto the road to create a wet condition and additional tests of each tire set were conducted. Overall, average deceleration levels did not vary significantly across the tires sets with tread depths from 7.1 mm (9/32″) down to 2.4 mm (3/32″) for both road surfaces in both dry and wet conditions. Compared to the deceleration levels at these larger tread depths, dry deceleration levels were greater for tread depths of 0.8 mm (1/32″) and 1.8 mm (2/32″) on both asphalt and concrete, and wet deceleration levels were lower for tread depths of 0.8 mm (1/32″) on both asphalt and concrete. These findings provide a source for analysts to estimate how tread depth affects deceleration for ABS-equipped vehicles.