In the United States, tire tread depth is measured in 32nds of an inch. New tires typically come with 10/32” or 11/32” tread depths. The original tread depth of a new tire can vary depending on the application and type of tire. The usable tread depth is calculated by subtracting 2/32" from the tires new tread depth. The U.S. Department of Transportation recommends replacing tires when they reach 2/32” . Many states legally require tires to be replaced at this depth.

To check tire tread depth, you can use the penny test. Place a penny between the tread ribs on your tire, with Lincolns head facing down. If the top of Lincolns head is visible, the tire has worn down to 2/32” and should be replaced. Check various points on the tire, around the circumference and between different ribs, to look for uneven tire wear.

Its important to note that tires lose some of their performance capabilities before reaching 2/32” of tread depth. As tire tread wears, it becomes less able to channel water, and the risk of hydroplaning increases, especially at higher speeds.