Tire Age Calculator (DOT Date Code)
Find how old a tire is from the 4-digit DOT date code on the sidewall (week and year), the approximate manufacture date, and when the 6-year and 10-year replacement guidelines are reached.
How it works
DOT date code WWYY: WW = week of manufacture (01–53), YY = year (20YY) · manufacture date ≈ Monday of that ISO week · age = check date − manufacture date · guidelines: inspect yearly from 5 years, many vehicle makers advise replacement at 6 years, tire makers set 10 years as the maximum
Every tire sold in the US carries a DOT (Department of Transportation) code, and its last four digits give the week and year it was made — "2321" means the 23rd week of 2021. Rubber ages even when a tire is unused, so old tires can crack and separate while the tread still looks deep. NHTSA notes that many vehicle manufacturers recommend replacing tires after six years and tire makers set a maximum of ten years, including the spare. Codes with only three digits are from before 2000 and are far too old to use.
Worked example
A tire stamped 2321 was made in week 23 of 2021, which began on June 7, 2021. Checked on October 5, 2026, it is 5 years 3 months old (5.3 years) — time for a yearly inspection. It reaches the 6-year mark on June 7, 2027 and the 10-year limit on June 7, 2031.
Sources: NHTSA — Tires: tire aging and the DOT code · 49 CFR 574.5 — Tire identification number (date of manufacture)
Frequently asked questions
How do I read the date code on a tire?
Find "DOT" on the sidewall and look at the last four digits of the code that follows, often inside an oval. The first two are the week and the last two the year: 0824 means the 8th week of 2024.
How old is too old for a tire?
Many vehicle makers recommend replacing tires after 6 years regardless of tread, and tire makers say no tire should be used after 10 years. Hot climates, sunlight and low use age them faster.
Is it OK to buy "new" tires that are a few years old?
Tires stored properly age slowly, and up to two or three years in storage is generally acceptable, but you are entitled to ask for recent stock. Check the DOT code before fitting.
Does the spare tire age too?
Yes. A spare that has never touched the road still ages; check its date code and replace it on the same schedule.
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This calculator is for educational purposes. Double-check important results before acting on them.