Did you know that tires have a date code on the side of each tire indicating when it was manufactured?
A tire identification number is required by the United States Department of Transportation (DOT) National Highway Traffic Safety Administration (NHTSA). All codes begin with “DOT” followed by 8 to 13 digits (letters & numbers); if the last number consists of only 3 digits, it was manufactured prior to the year 2000.
Here are examples of Tire Identification Numbers (TIN) and how to read them:
After the year 2000:
DOT BB 9N LMLR 1817
DOT (Department of Transportation)
BB (Manufacturer & Plant Code)
9N (Tire Size Code)
LMLR (Manufacturer Identity Number)
1817 (Date Manufactured)
The last four digits are the important ones. In this example, “18” is the week it was manufactured and “17” is the year. So this tire was manufactured on the 18th week of 2017.
Before the year 2000:
DOT EJ6K DFM 235
DOT (Department of Transportation)
EJ6K (Manufacturer & Plant Code)
DFM (Manufacturer Identity Number)
235 (Date Manufactured)
The last three digits indicate the tire was manufactured on the 23rd week of the 5th year of the decade. Tire manufacturers assumed their tires wouldn’t last longer than 10 years. There is no way to tell from the above number which decade the tire was manufactured, for example, it could mean 1985 or 1995.
Can’t find the Tire Identification Number? It may be on the opposite sidewall, the manufacturers are only required to place the number on one sidewall, not both.
Tires don’t have an actual expiration date, only recommendations by tire and car manufacturers. Tire manufacturers recommend visual inspection of tires after 5 years and replacement at 10 years, regardless of tread wear. Car manufacturers vary, but most manufacturers recommend tire replacement after 7 years.
Because of oxidation, tires lose elasticity, harden and become brittle. This oxidation occurs with or without use and increases in warmer climates. Even tires stored inside can become unsafe to use after 5 years. Tires being stored should be wrapped in plastic and stored in a cool, dark place to slow oxidation. If you have a car you only drive a couple of thousand miles per year, knowing how old the tires are and performing visual inspections is just as important as remaining tire tread depth. Add visual inspections of tire condition to your routine maintenance schedule. Besides checking the tread depth and looking for uneven wear patterns, look for cracks in the rubber which indicates tire degradation.
Contact us with any questions, comments, or your personal experience with aged tires. Stay safe on the road and enjoy your journey.