To measure tire tread depth, you can use several simple methods: 1. Penny Test (U.S.)

• Insert a penny into the tire tread groove with Lincoln’s head upside down and facing you.
• If you can see the top of Lincoln’s head, the tread depth is less than 2/32 inch, and the tire needs to be replaced.
• If the tread covers part of Lincoln’s head, the tire still has adequate tread

2. Quarter Test (U.S.)

• Insert a quarter into the tread groove with Washington’s head facing you.
• If the tread touches Washington’s head, you have at least 4/32 inch of tread remaining, which is safer than the minimum

3. 20p Test (UK)

• Insert a 20p coin into the tread groove.
• If the outer band of the coin is visible, the tread is below the legal minimum of 1.6mm and the tire should be inspected or replaced

4. Tire Tread Depth Gauge

• Use a purpose-made tread depth gauge, available at auto parts stores.
• Insert the probe into the shallowest tread groove and press the base of the gauge flush against the tire.
• Read the measurement, usually in 32nds of an inch or millimeters.
• Repeat at multiple points and use the lowest reading to assess tire condition

5. Tread Wear Indicator Bars

• Most tires have built-in tread wear bars molded across the grooves.
• When the tread is flush with these bars (usually at 2/32 inch), the tire must be replaced

Recommended Replacement Depths:

• Replace tires at 2/32 inch tread depth (minimum legal limit in most U.S. states).
• Consider replacing at 4/32 inch for better wet traction and safety, especially in adverse conditions

Regularly checking tread depth helps ensure safe driving by maintaining traction and reducing hydroplaning risk. In summary, the easiest home method is the penny test, but for precise measurement, a tread depth gauge is best. Always check multiple points around the tire and replace tires when tread is worn to or below 2/32 inch