A tire’s tread pattern channels away water and maximizes the tire’s contact with the road. As a tire wears, its grooves become shallow and displace less water. When tread depth drops below 4/32″, a vehicle takes longer to stop on wet roads and risks hydroplaning—losing contact with the road.
To illustrate tire safety and the impact of worn tires, AAA measured the stopping distance of new all-season tires and the same tires worn to 4/32″, as they decelerated from 60 to 0 mph on a wet road. Here’s what we found:
- Vehicles with worn tires went an average 87 feet beyond those with new tires before stopping—more than the length of a semi-trailer truck.
- Vehicles with worn tires were still traveling nearly 40 mph at the point when those with new tires had come to a stop.