Technical Article

How Old Are Your Tires

(as appeared in the Winter, 2012 TSR)

By Art Fournier

As editor, I get copies of several other clubs’ newsletters. The August 2012 edition of the Shenandoah Valley British Car Club’s newsletter had an informative article on how to determine the age of your tires, which caused me to look into the subject.

Tire age should be particularly important to us as drivers of cars that have been out of production for 30 years or more. Tires age and should be replaced before they become dangerous and prone to failure.

So, just how do you determine a tire’s age? Simple: By law the answer is right on the tire as part of the U.S. Department of Transportation (DOT) identification number. The number may be found near the rim and should begin with “DOT” indicating the tire met all applicable federal standards. This will be followed by characters identifying the plant where the tire was made and its manufacturer. Finally, there will be three or four numbers indicating the week and year of manufacture. Tires manufactured before 2000 will have three numbers; tires manufactured after 2000 will have four. For example, {317” indicates a tire was manufactured in the 31st week of 1997, and “3107” indicates the tire was made in the 31st week of 2007. If you can’t find the identification number on the outside of the tire, it will be on the inside.

There’s a lot of other information coded into the various letters and numbers on your tires. The U.S. DOT has a web site that can help you decode these:

How old is safe? The National Highway Traffic Safety Administration recommends tires be replaced every six years regardless of mileage or use. That can be a hard pill for us to swallow when you consider that most of our LBCs are only driven a few thousand miles per year. However much tread a tire has, the rubber in the tire begins to deteriorate as soon as it’s manufactured due to wear, temperature and sunlight. At some point, the rubber will break down and become prone to blowout or tread loss. And don’t forget that spare that’s been lurking in the trunk for who knows how long!

Sure there are are bragging rights associated with those original redlines. But don’t take a chance with old tires, especially during a “spirited” club driving event. Take a look at your tires. If the age code has three digits, you’re well past its safe lifetime and should be shopping for new tires!

This article appeared in a recent issue of The Standard, newsletter of the Capital Triumph Register.

Air Pressure in T-Series Tires

Milton Babirak noted that this topic caused considerable discussion among members taking part in the recent Fall Ramble. He had been putting as much as 40 psi in his TD’s tires, while others advocated using as little as 26 or 28 psi. This prompted him to research the issue online via the MG BBS web site ( which produced recommendations ranging from 24 to 32 psi, although there seemed to be a consensus in favor of 26 psi (front) and 28 psi (rear). Several Ramble participants stressed the importance of having a reliable tire pressure gauge, since they viewed most of the ones on the market as inaccurate. Milton plans to drop by his local Firestone dealer to see what kind of gauges they use.

Comments from readers will be appreciated.