Aging of Tires

There has been a lot of media coverage in the last few years about the problems tires have when they get too old. Most tire professionals have known about this for years and it's not just media panic, it is a serious issue. When tires get old, the rubber loses is elasticity (gets hard) and then when the tire heats up, the tread tends to blow right off. This can cause you to lose control of the vehicle, and it almost always causes some damage to the vehicle. Also, it doesn't matter whether or not the tire has been exposed to the elements, the rubber still gets hard over time. The industry standard useable age limit for tires is 6 years, and we know of no manufacturer that will warranty any tire older than that. Therefore, because it is a safety issue, we recommend against using any tire more than six years old, and we cannot service them. Granted, this type of failure can also happen to tires less than six years old when they heat up, but as the tire ages, the chances of having this problem go up dramatically.

How to check the date code:

On both sides of all tires near the rim, there is a Department of Transportation code or "DOT" number. It is preceded by, you guessed it, the letters DOT. However the date code is (usually) only found on one side of the tire. Most DOT numbers have between 6 and 8 letters/numbers mixed, and then the date code follows that. From the year 2000 on, the date code has been 4 digits, the first two are the week of manufacture and the second two digits are the year of manufacture. For instance 2407 would signify the 24th week of 2007. However, before the year 2000, the date code was only 3 digits, so the first two would be the week of manufacture, and the last would be the year, so without any listing of decade, a 247 date code could either be the 24th week of 1997, 1987,  or 1977  (Date stamps went back at least to the 1970s). No matter what decade it is, anything with a 3 digit date code is too old and would definitely be an unsafe tire to use. Below are several examples showing how to check the date code and what happens when the tires get too old. All of these tires just happened to be handy at the time of this post.

Here is an example to show how to check the date code. This is a new tire of course. Notice the picture on the left, you can only see the OT of DOT, but notice there are 7 letters and numbers and then the date code "4910" means that this tire was built in the 49th week of 2010. The right side picture is the same tire's DOT code on the other side. Not only is the date code missing, but the last three digits are gone too. This is actually pretty common, but more tires would have all 7 digits on the other side but not the date code.

Here are a couple of examples of older tires and what happened to them:

Notice the first tire's date stamp reads 4204 so this tire was built in the 42nd week of 2004. The second tire has an extra (circled) set of digits after the date code that read 1803, that is not the date code, the date is the one right at the end of DOT number that reads 128. So this tire was made in the 12th week of 1998 or 1988. You do have to watch out for these other numbers, again, only the numbers directly at the end of the DOT number are the date code.

Lastly, here is another example of pre-2000 dated tire, and what happened to it. This one is stamped 148 having been made in the 14th week of 1998. This one would have blown the tread off soon had it not been removed. Notice that it also still has good tread. Unfortunately, good tread is no guarantee of a safe tire.

Back To Tires 101