How Old Is That Tire? Reading the DOT Date Code

Tread depth does not tell you a tire is safe. In West Texas sun, age matters as much as wear.

A tire with plenty of tread can still be finished, and out here it frequently is. UV, heat and ozone break rubber down whether the tire is being driven or sitting on a trailer behind a shop.

Finding the date

Look for the DOT code on the sidewall. The last four digits are the manufacture date: the first two are the week of the year, the second two are the year. 3223 means the 32nd week of 2023.

It is often only on one side of the tire, so if you cannot find it, check the inboard sidewall.

How old is too old

There is no single legal figure, and manufacturers differ. The common guidance is to have tires inspected annually from around five years and to replace them somewhere around six to ten years regardless of tread. In this climate, lean toward the earlier end of that.

What ageing looks like

• Dry rot — fine cracking in the sidewall or between the tread blocks. Once it is visible the tire is on borrowed time.
• Hardening. Old rubber is harder, which means less grip, particularly on a wet road.
• Chalky or grey appearance rather than deep black.
• Sidewall cracking at the flex point, which is where the structure is working hardest.

Buying "new" tires that are not

Tires sit in warehouses. A tire sold as new can legitimately be a few years old, and its clock has been running the whole time. Check the date code on anything you buy — it is a fair question and any honest seller will show you.

What slows ageing

Keeping tires out of direct sun where you can, keeping them at correct pressure (an underinflated tire flexes more and degrades faster), and driving the vehicle — a tire that sits still develops flat spots and ages without the flexing that keeps the compound working. Trailers that sit all year are the classic case.

We check date codes as part of every tire inspection. Call and we will come look at what you have.