Tire age calculator (DOT date code)

Every tire sold in the US carries a Tire Identification Number after the letters DOT. The first characters identify the factory, size and manufacturer's codes; the last four digits are the date:

• First two digits: the week of manufacture (01–53)
• Last two digits: the year (23 = 2023)

Example: DOT U2LL LMLR 2423 → week 24 of 2023, which is around mid-June 2023.

The full code is printed on at least one side of the tire, often in a small oval; the other side may show only a partial code, so check both. Tires made before 2000 used a three-digit date code (week plus the last digit of the year), which doesn't reveal the decade. The calculator recognizes these and tells you the tire is at least 25 years old.

Rubber ages even when a tire has plenty of tread: it hardens, develops fine cracks and loses grip, and the risk of tread separation increases. There is no single US law that sets a maximum tire age for passenger cars, but many vehicle and tire manufacturers publish recommendations, commonly to have tires inspected annually after about five years and to replace them at about ten years from the manufacturing date regardless of tread. Check your vehicle owner's manual and the tire maker's guidance.

The calculator flags tires older than 10 years. Heat speeds up aging, so tires in hot climates, on vehicles parked outdoors, or on RVs and trailers that sit for long periods may need replacing sooner.

Say your car's tires read 0921, 0921, 3518 and 3518. The front pair was made in week 9 of 2021 (late February to early March 2021) and the rear pair in week 35 of 2018 (around late August 2018). As of late 2026, the fronts are about 5 years 8 months old and the rears about 8 years 2 months old. Even with good tread, the rear pair is approaching the age many manufacturers recommend for replacement, so it is worth having them inspected and planning ahead.

Tires can sit in a warehouse for months before they are sold. When you buy new tires, look at the date code; a tire a few months old is normal, but you may want to ask for fresher stock if it is already several years old. The same check is important when you buy a used car, used tires, or a vehicle with a full-size spare that has never been used: the spare can be much older than the tires on the road.

Manufacturers number weeks slightly differently (which weekday a week starts on), so the date range is accurate to about ±1 week. The calculator shows the age in years with one decimal and as years and months.

Age is only one factor. Replace a tire at any age if you see cracks in the sidewall or tread, bulges or blisters, cords showing, or tread worn to 2/32 inch, where the wear bars become flush with the tread. Keeping tires properly inflated and rotated helps them last.

For the cost side of driving, the gas mileage calculator shows your fuel economy and cost per mile.

The National Highway Traffic Safety Administration (NHTSA) publishes tire safety guidance and lets you look up tire recalls. If a tire you own is recalled, the tire identification number, including this date code, tells you whether it is affected. Register new tires with the manufacturer so you are notified about recalls.