Tire Tread Depth Calculator
Measure your tread, tell us how much you drive, and find out how many miles are left before the tires are legally worn out.
Your tires
- Measure the shallowest main groove. Uneven wear across a tire means an alignment problem, not just a worn tire.
- Wear bars sit at 2/32. If the tread is flush with them the tire is legally worn out.
- Tires age out as well as wear out. Six years is the usual limit regardless of remaining tread.
What the thresholds mean
2/32 of an inch is the legal minimum across most of the United States, and it is the point where the moulded wear bars sit flush with the tread. That is a legal floor, not a recommendation.
4/32 is where wet performance falls apart. Tread grooves exist to move water out from under the contact patch, and below 4/32 there is not enough volume to do it. Wet stopping distances stretch dramatically and hydroplaning starts at lower speeds.
6/32 is the practical floor for snow. A tire with less than that cannot pack snow into the grooves, which is how a winter tire actually generates grip on snow.
The penny test and why a gauge is better
A penny inserted head down shows 2/32 when the tread reaches the top of Lincoln's head, which only tells you whether the tire is already illegal. A quarter reads about 4/32 and is a more useful early warning.
A tread depth gauge costs a couple of dollars and gives you an actual number, which is what you need to work out how long the tires have left rather than just whether they are finished.
Measure in several places
Check the inner groove, the centre and the outer groove on each tire. A tire worn on both edges but not the centre has been run underinflated. Worn in the centre only means overinflation. Worn on one edge is camber, and feathered edges are toe. The pattern tells you what to fix so the next set lasts.
Frequently asked questions
At what tread depth should tires be replaced?
2/32 is the legal minimum, but 4/32 is the sensible replacement point because wet grip falls off steeply below it. If you drive in snow, replace at 6/32, since below that a tire cannot generate snow traction.
How many miles does 1/32 of tread last?
Roughly 3,000 to 5,000 miles for a typical passenger tire, though it varies enormously with compound, alignment, inflation and driving style. This calculator works out your own rate if you tell it how many miles are on the current set.
Do tires expire even with tread left?
Yes. Rubber hardens and the structure degrades whether or not the tire is used. Six years from the manufacture date is the common guidance and ten is an absolute limit. The date is on the sidewall as the last four digits of the DOT code, week then year.
Why are my tires wearing unevenly?
Both edges worn means underinflation. The centre worn means overinflation. One edge means a camber problem. A sawtooth feel across the tread means toe. Cupping or scalloping usually points at worn dampers.
Everything on this page is an estimate worked out from the numbers you entered and typical figures for the conditions you picked. Your vehicle, your parts and your conditions will differ. Check anything you intend to act on against the manufacturer's specification, the service manual, or a qualified technician. Verifying the result before relying on it is up to you.