TireSizeCalc

How to check tire tread depth

Replace a tire when its tread wears down to 2/32 in. This guide shows three ways to check the tread.

Last reviewed · 2 source documents · Written in ASD-STE100 Simplified Technical English

When to replace a tire

NHTSA tells you to replace tires when the tread wears down to 2/32 in. NHTSA says that tires are not safe at that depth.1 State laws on minimum tread depth are different from state to state. Read the rule for your state.

1. Look at the wear bars

Each tire for a light vehicle has at least six tread wear indicators around the tire.2 The indicators are bars that rise from the bottom of the grooves, between the tread blocks.1 They show when the tread wears down to 1/16 in, which is 2/32 in.2

  1. Find the small raised bars across the bottom of the main grooves.
  2. Compare the tread surface with the bars.
  3. If the tread is level with the bars, replace the tire.1

2. Do the penny test

  1. Put a penny in a groove. Put Lincoln's head upside down and toward you.1
  2. If you can see the top of Lincoln's head, replace the tire.1
  3. Do the test in the inner, center and outer grooves.

3. Measure with a tread depth gauge

  1. Push the probe of the gauge into a main groove until the base is flat on the tread.
  2. Read the depth in 32nds of an inch.
  3. Measure the inner, center and outer grooves. Use the lowest value.
  4. Enter the value in the tread depth calculator to see the tread that is left.

How often to check

Check the tread at least one time each month, when you check the tire pressure.1 Also read the date code on the tire. See how to read the tire date code.

More guides

Printed from https://tiresizecalc.net/guides/tire-tread-depth/. Figures as published on 2026-11-01. The sources are listed below.

Sources

  1. Tires (Tire Safety). National Highway Traffic Safety Administration (NHTSA). Undated web page. Tread. Retrieved 2026-11-01.
  2. 49 CFR 571.139 - Standard No. 139; New pneumatic radial tires for light vehicles. National Highway Traffic Safety Administration (NHTSA), Code of Federal Regulations (eCFR). 49 CFR 571.139. eCFR up to date as of 2026-10-15. S5.4. Retrieved 2026-11-01.

Last reviewed 2026-11-01. The full source list, with dates and file checksums, is in How the numbers are calculated. To report an error, email contactus@tiresizecalc.net.