It is important to know the age of your tires because tire manufacturers recommend that tires should be replaced every six to ten years. It is also important to consider that rubber ages whether or not the tires are used.
Determining the Age of Your Tires
Question: I need to find out how old my tires are. How can I do this?
Answer: That’s easy! Just get out the receipt from the purchase of your tires. Of course, that’s an obvious answer, but what if you can’t find your proof of purchase?
Here’s another common situation. You are considering buying a car that has been advertised “by owner”, but you have a question about the age of the tires. Other than believing the seller, how can you find out?
The Dot Number
When you bought your last set of tires, you may have noticed a lot of numbers and letters on the sides of the tires. You may have assumed that these were numbers placed there for the manufacturer’s purposes, and you did not place any particular significance to them. However, if you look for the letters, “DOT” and examine the 10-12 numbers following these letters, you can find out the information you seek about your tires. The U.S. Department of Transportation requires that the manufacturer place the manufacturers code, the tire size, and the week, year and the place where the tire was manufactured on the sidewall of the tire. The information varies slightly depending upon the year the tires were manufactured.
The Year 2000 To Present
On these newer tires, it is fairly easy to determine the age of the tires. The last four numbers of the DOT code signify the date of manufacture. For instance, if the numbers are 0308, your tires were manufactured in the third week of 2008. Very simple, right?
Before Year 2000
Determining the age of tires made before the year 2000 is more difficult and the numbers can create some confusion. For these tires, the date of manufacture is the last three numbers of the DOT code. For instance, if the code numbers are 038, the tires were made in the third week of the year and the eighth year of the decade. The problem is there is no way to determine WHICH DECADE. Therefore, the tires could have been manufactured in 1988 or 1998.
What About a DOT Number That Appears to Be Incomplete?
Currently the DOT only requires that the the date code be placed on one sidewall of the set. If the number is incomplete, just look at the sidewalls of the other tires.
Importance of Keeping Your Tires Purchase Receipt
Now that you know how to determine the age of your tires, if you lose your receipt, it’s no big deal, right? Wrong! Most manufacturer’s warranties on tires are good for four years from the date of purchase, or five years from the date the tires were manufactured. For instance, if you bought new tires this year, but the tires were manufactured, say two years ago, your warranty would be good for four years. However if you did not have a proof of purchase, your warranty would only be good for three more years. You have just lost one year of your coverage.
What Other Factors Can Help Determine If I Need New Tires?
Beside knowing the age of the tires, there are other factors to consider whether or not whether or not the tires should be replaced. Remember that the climate and road conditions in which the tires were driven also have a bearing on how long the tires will last.
Simple tests you can do yourself to help you make your decision
Testing Tread With a Penney
In the U.S., the measurement of tread depth is done in 32nds of an inch. A typical new tire has between 10/32 inches to 11/32 inches. According to the U.S. Department of Transportation, tires should be replaced at 2/32 inches. You can test the depth of your tire tread with a penny; here’s how: Place the penny in the tread with Lincoln’s head pointing down. If the top of Lincoln’s head is covered by the tread, you tread has not yet reached the 2/32 inch mark. If you can see Lincoln’s whole head, it is probably time to replace the tire. You can also test the tread depth by purchasing a tread depth gauge at your auto parts store. The tread depth gauge reads tread depth in both millimeters and 32nds of an inch.
Tread Indicator Bars
The newer tires come with “wear bars” embedded in them at 2/32 inches. If the tread is even with the indicator bars, it’s replacement time.
Check the Sidewalls
Cracks or cuts in the sidewall can be indicators of problems such as a leak or a blow-out waiting to happen. If you see this kind of damage starting to happen, check with your repair technition to help you determine if you need to change your tires.