How to Measure Tire Tread Depth
A practical guide for collecting safer, more consistent tread depth measurements.
Use the right tool
Use a tire tread depth gauge. Do not rely on photos, coins, phone apps, or visual guessing when you need a value for wear-rate calculations.
Record measurements in either 32nds of an inch or millimeters. Keep the same unit for the entire tire.
Measure by groove and position
Most tires have fewer than 8 measurable main grooves. Measure only the grooves that actually exist on the tire.
For a quick check, one position around the tire can be used. For a better average, measure up to three positions around the tire, approximately 120 degrees apart, when that can be done safely.
Example: a tire with 4 measurable grooves and 3 positions produces 12 measurements. A tire with 8 grooves and 3 positions produces the maximum 24 measurements.
If measuring on the vehicle
If the tire remains on the vehicle, only lift the vehicle using manufacturer-approved jacking points, support it with properly rated jack stands, work on a level surface, chock the wheels that remain on the ground, and never rely on a jack alone.
Do not place yourself under an unsupported vehicle. If a measurement position cannot be reached safely, skip that position or have the tire inspected by a qualified tire professional.
How to use the average
The measurement average is a better input than a single tread reading because it reduces the effect of one unusual groove or one unusual point around the tire.
Use the calculated average as the current average tread depth in Treadsley wear-rate tools.
Important safety and limitation notice
This guide is for general educational use. It does not determine whether a tire is legal, safe, roadworthy, repairable, or acceptable for continued use.
Tire serviceability can be affected by tread depth, age, cracking, punctures, exposed cords, sidewall damage, bulges, impact damage, inflation pressure, load, alignment, and operating conditions. Have questionable tires inspected by a qualified tire professional.