Most drivers can tell you their tire size but almost none can tell you their tires’ birth date. That matters, because tires degrade from the inside out even when the tread looks fine — and age, not wear, is what makes old tires dangerous. Here is how to find your tire’s age in under a minute, why the date matters, and when it is time to replace.
Where to Find Your Tire’s Age: The DOT Code
Every tire sold in the US has a DOT code stamped on the sidewall — a sequence starting with “DOT” followed by letters and numbers. The last four characters are the date code. The first two are the week, the last two are the year. A tire stamped 3219 was made in the 32nd week of 2019. A code with only three digits (e.g. 329) means the 32nd week of 1999 — a tire that old should be replaced immediately, no questions asked.
If the sidewall is hard to read, check the inner side of the tire or use a flashlight — and remember the code is on every tire, so check all four (and the spare). If you would rather not decode it manually, use our Tire Age Calculator — enter the DOT code or the manufacture date and it tells you exactly how old the tire is in years and months.
The 6-Year and 10-Year Rules
- 6 years: Most tire manufacturers (Michelin, Bridgestone, Goodyear, Continental) recommend replacing tires once they reach 6 years of age, regardless of tread depth.
- 10 years: Industry consensus and NHTSA guidance say no tire should be used beyond 10 years from its manufacture date — even if it has never been mounted.
- Spare tires: The spare ages too, even sitting in the trunk. Temperature swings in the cargo area accelerate rubber degradation.
These are not marketing suggestions. Rubber compounds harden and lose elasticity over time, which is why an old tire with full tread can still fail catastrophically on the highway.
Visual Warning Signs of Aging Rubber
- Sidewall cracking: Small crazing lines or deeper cracks in the sidewall rubber are the classic sign of oxidation and aging.
- Dryness or chalkiness: Rubber that looks dull, gray, or dry to the touch has lost its protective compounds.
- Bulges or blisters: These indicate internal belt separation — replace immediately.
- Vibration at speed: A tire that vibrates after sitting for years may have developed flat spots or internal damage.
Use the Tire Age Calculator to get the precise age in months — then pair that number with a visual inspection to make the call.
Who Should Be Most Concerned About Tire Age
- Used-car buyers: A 2018 car may have its original 2018 tires — fine for tread, risky for age. Check the DOT code before you buy.
- RV and trailer owners: Trailer tires sit for months between trips and are a leading cause of RV blowouts.
- Occasional drivers: Low mileage means tires age out long before they wear out. A 3,000-mile tire that is 8 years old still needs replacement.
- Anyone with a spare: Full-size spares older than 10 years should be replaced, not “saved for emergencies.”
How to Calculate Tire Age
The math is simple once you have the date code: count the months from the manufacture date to today. A tire from week 20 of 2021 is roughly 5 years old in mid-2026. But “roughly” is not good enough when a blowout at highway speed is the alternative — that is exactly what a dedicated tire age calculator is for. Enter the week and year, and it handles the month-by-month count precisely.
Bottom Line
Read the DOT code today. If your tires are 6+ years old, plan a replacement even if the tread looks fine; if they are 10+ years old, do not drive on them. The few minutes it takes to check could be the difference between a routine trip and a tire failure at speed. Check your tires’ age now with the Tire Age Calculator.
