Every tire sold in the U.S. since 2000 has a DOT date code stamped on the sidewall. It's small, often on the inner sidewall, and easy to miss — but it tells you something the tread depth can't: how old the tire is. And age, more than mileage, is what kills tires.
What it looks like
Look on the sidewall for a string starting with the letters DOT followed by a long character code. The last four digits are the date stamp: two digits for the week of the year, two digits for the year.
Example: DOT B9 7K HXAR 2723. The 2723 at the end means the 27th week of 2023 — early July 2023.
Pre-2000 codes were three digits
Tires made before 2000 used a three-digit code that didn't account for the decade. If you find one of those, the tire is old enough that age alone justifies replacement.
What ages a tire
Heat, UV light, ozone, and time all break down the rubber compound. A tire stored indoors at moderate temperature ages slower than one parked outdoors in Arizona. But all tires lose elasticity over time — the rubber becomes harder and less able to grip the road, and microscopic cracks start to form in the casing.
Service-life rules of thumb
- 6 years from build date — most manufacturers' recommended service limit (Michelin specifies this)
- 10 years from build date — hard ceiling, replace regardless of tread or condition
- 5 years on a spare — even unused, a spare older than 5 years is suspect
Why this matters for used tires
A used tire can have plenty of tread but still be past its service life. When buying used, always ask for the DOT date code. We never ship anything older than six years from today's date. If a seller can't or won't tell you the date code, don't buy.
Where to find it on hard-to-read tires
Some tires only stamp the full DOT code on the inner sidewall (facing the vehicle). If you can't find it on the outside, you'll need to either crawl under and look or have the wheel turned to expose the inner face. Every tire has it somewhere.
Tread tells you how much rubber is left. The DOT date tells you whether that rubber is still alive.