Measuring Tire Tread Depth with a Tire Gauge(Lea en español)
While U.S. coins can be used to estimate remaining tread depth as a tire approaches the end of its useful life, the established method of measuring remaining tread depth in the U.S. is with a gauge that reads in 32nds of an inch (other countries measure tread depth in millimeters). Typical tire tread depth gauges measure up to 32/32nds (or 25-26mm) since almost all passenger car and light truck tires begin with less than one inch of tread depth.
To use a tread depth gauge, follow the steps below.
Step 1: Confirm which measuring scale you are using. Some tread depth gauges measure in 32nds of an inch (left), while others measure in both 32nds of an inch and millimeters (right).
Step 2: Push the tread depth gauge against a hard, flat surface to confirm it "zeros out" when fully compressed.
Step 3: Push the measuring scale into the gauge as far as it will go.
Step 4: Place the probe into the center of a circumferential tire groove and push down on the gauge's base.
Step 5: Do not place the probe on the molded tread wear indicators or on any raised surfaces of the tread design.
Step 6: Carefully remove gauge by holding its barrel (without touching the probe) and confirm the tread depth reading.
Step 7: Place the probe into additional locations around the central circumferential tire groove at lease 15 inches apart and repeat.
Step 8: Place the probe into the inner and outer circumferential grooves and repeat.
Step 9: Average all readings.
Step 10: Identify the percentage of tire wear by confirming the tire's original/new tread depth in its specs compared to the remaining tread depth just measured.
Note: Incorrect air pressure, vehicle alignment, loose or worn parts, driving conditions, load, etc, can cause rapid or uneven tire wear. An accurate tread depth gauge can detect developing wear patterns earlier than simply looking at the tread. This often allows the cause to be identified and corrected before excessive or irregular tread wear ruins the tire.