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

The effect of tire tread depth on the performance of anti-lock brake systems (ABS) in newer vehicles is not well studied. A single ABS-equipped SUV was used to perform a series of 216 ABS-engaged braking tests on dry and wet asphalt and concrete surfaces using uniform sets of 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 data sampled at 200 Hz. Tests were initially conducted on a dry surface, with tire sets changed between tests. A water truck then distributed water onto the road to create a wet condition and additional tests of each tire set were conducted. Deceleration levels did not change significantly from 7.1 mm (9/32”) down to 2.4 mm (3/32”) of remaining tread on both surfaces in both conditions. Compared to the deceleration levels at these larger tread depths, dry deceleration levels increased for tread depths of about 0.8 mm (1/32”) and 1.8 mm (2/32”) on both asphalt and concrete, and wet deceleration levels decreased for tread depths of about 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.