Tire Tread Depth
Replace any tire with a tread depth of less than 1/16 in (1.6 mm).
Tread wear indicators are located in at least three places on the tread circumference and become visible at a tread depth of approximately 1/16 in (1.6 mm). The tread wear indicators appear as a solid band across the tread.
You may also use a depth gauge or an accurate ruler to measure the depth of the center tire tread on both front and rear tires.