The tire industry has some loose guidelines on tire age that call for tire replacement after 6 to 10 years of service. On a daily driver, you'll likely wear out the tread before the 6 to 10-year window, but on our classic cars, the tires could expire well before the tread is gone. Even if a car is stored inside and the tires pass a visual inspection (no cracks, dry rot or other visible deterioration) we typically suggest replacement after 10 years if you plan on driving it.
So, what happens if you drive on a tire that is more than 10 years old? You could be lucky and the tire could last until the tread is worn down, or the tire could separate without warning. Even without noticeable defects, the tire could be susceptible to sudden delamination or separation due to the heat buildup from driving. No one wants to have a blowout.
So, how do you determine the age of your tires so you can confidently drive on them?
Four-Digit Tire Codes:
Decoding a tire and determining its age is a pretty straightforward process. Look for the tire identification number, often called a DOT number. For tires built after the year 2000, the date code features four digits, and most DOT numbers have 12 digits.
The date code resides at the end of the DOT number. The first two digits of the date code are the week of production and the last two are the year of production. The example above is from my 2004 Thunderbird. The date code of 16 would let you know that the tire was built in the 16th week of a year ending in 2018. So, the tires on my 2004 Thunderbird are still within the 6 to 10-year window.
Three-Digit Tire Codes:
Some manufacturers used date codes prior to 1971, but there wasn’t a standardized system, so each brand handled numbering differently. Tires built before 2000 featured a three-digit date code at the end of the DOT number. There could be confusion about whether the digit refers to 1978, 1988 or 1998, so let’s dig a little deeper.
The example above are the old tires that were on my 1955 Thunderbird when I first got the car. The first two digits of the date code are the week of production, and the last digit is the year of production. The date code of 47 would let you know that the tire was built in the 47th week of the year ending in 1978.
Sometimes you can easily determine which decade the tire belongs in based on the sizing nomenclature, brand or style.
doug7740
1955 Thunderbird Blue
