How to Use the Tire DOT Age & Replacement Guide
Every tire sidewall carries a string starting with "DOT," and the last 4 digits tell you exactly when it was made. The first 2 digits are the week of production, and the last 2 are the year. For example, "2318" means the tire was made in the 23rd week of 2018.
The DOT code originated with the US Department of Transportation and became the standard 4-digit format required on tires sold in the US since 2000 — it's now the reference point used internationally. Enter just those last 4 digits and this calculator works out the tire's exact age.
Even a tire with plenty of visible tread can be unsafe once the rubber compound ages: it hardens and develops micro-cracks that reduce grip, especially in wet conditions. Tire makers generally recommend a professional inspection once a tire passes 6 years old, and replacement regardless of tread depth once it passes 10 years.
This is especially easy to miss on a spare tire, a car that's been parked for long stretches, or any tire that sees low mileage — the tread looks fine, so age gets overlooked. Making a habit of checking the DOT code alongside tread depth during routine maintenance is a simple way to catch this before it becomes a safety issue.
Frequently Asked Questions
It's stamped on the tire sidewall in a string starting with 'DOT'. The last 4 digits are the manufacture date: the first 2 are the week and the last 2 are the year (e.g. 2318 means the 23rd week of 2018).
Even with plenty of tread left, most tire makers recommend inspection after 6 years and replacement after 10 years regardless of wear, since rubber hardens and develops cracks over time.