This simple bit of knowledge can come in handy when buying a used car, pulling a car out of long-term storage, or inspecting used tires. The key thing to remember is that tires are not like vintage wine – they do not age well. Even without visual symptoms like stress cracks or splits in the tread, tires still deteriorate over time. According to the tire industry, the average effective lifespan is less than 10 years.
Tire manufacturers began dating tires in the 1970s, but the code changed at the beginning of the 21st century. The current process for any tire built since 2000 is an embossed code on the sidewall starting with the federal government’s Department of Transportation (DOT) followed by a series of letters ending in four digits. The first two numbers are the week of manufacture with the second two digits being the year. So a code of 2919 means that the tire was built in the 29th week of 2019.
Before the year 2000, the code was only three digits and far less accurate. Again the first two numbers represented the week while the final number was the year. So a date code listed as 299 would represent the 29th week of 1979, 1989, or 1999. This makes accurately determining the age of these earlier tires a guessing game. But frankly, any tire from even 1999 is well into its second decade and unless the tire is historically significant, it’s certainly not worth using.
One way to date three-digit code tires would be based on the sizing. If the tire is using a P-metric designation like 255/40R16 for example, then this is probably a tire from the late ’80s or perhaps early ’90s, since that’s when the P-metric sizing began. If the size uses the older alpha-numeric sizing (L78-15 for example), then that’s likely a ’70s tire as this designation started in 1967.
The tire industry standard for the age of tires maintains that a tire more than 6 years old, regardless of tread condition, should be replaced. This is not a hard and fast rule, but more of a safety guideline. In many states, like California, tire stores will not service a tire that is more than six years old, for liability reasons. But if you know the age of your tires, you at least will have some information that will make your next project a little safer.