Most drivers never read their tire date codes. Its not surprising as few are aware that outside of tread wear and tire punctures, tire age is a leading cause of tire failure. Tires age and deteriorate over time when the are exposed to heat and oxygen. The two combine to break down the layers that are meant to hold a tire together. The National Highway Safety Administration (NHTSA) who is charged with ensuring the safety of the United States roadways, states “we do know that tire aging is a significant factor in tire related safety”. This information is important as most experts, inside and outside of government, agree that “Old tires are also subject to greater stress, which increases the likelihood of catastrophic failure”. Yet few people are aware that they can even check the age by checking the side of their tires.
How to check on tire age
The best way to check a tire’s age is to check the Department of transportation (D.O.T.) code on the tire. By law, all tires designed to be driven in the United States are required to stamp the D.O.T. code into the rubber. This code is often located around the bead of the tire and should not be confused with the standard tire codes which is used to describe the tire’s key physical characteristics. The code starts out with the word DOT and may contain up to 11 numbers and letters after the word. There are sometimes other numbers or letters after this code, but these are reserved for the tire manufacture’s use and are not related to the code.
The D.O.T. values specifies information like the company, location, mold number, batch, and most importantly the date of production. The values were originally designed to allow consumers to quickly identify if their tires are part of a certain batch if a problem was ever discovered with a set of tires. The last 3 or 4 numbers in the code are the tire date codes. If the tire was manufactured before January 1st 2000, the last 3 digits of a DOT number represented the week (2 digits) and the year (1 digit) of production. For example, if the last three digits are 063, the tire was produced in the 6th week of 1993. There is often a triangle after the single year digit. Tires produced after January 1, 2000 have a 4-digit date code at the end of the DOT number. The first 2 digits represent the week of production and the final 2 digits represent the last 2 digits of the year of production. For example, in the picture the 4104 indicates that this tire was manufactured on the 41stweek of 2004.
When purchasing new tires for your vehicle, you should always check the tire date codes first. If the tire was manufactured more than six months earlier, consider asking the salesperson for newer tires. Even though the tires have never been used, they may have started to degrade from heat and exposure to oxygen. In particular, many tire manufacturers will issue tire rebates for older tires in order to help clear out inventory of a batch before they age too much. Most tire shops will often have inventory of old as well as new stock of tires so they will happily let you select from the newer batch. On the other hand, older tires are harder to return to an internet retailer.