We're all familiar with the old saying, "You can't judge a book by its cover." Well, the same goes for tires, looks can be deceiving. The inner layers will slowly deteriorate over time even when the tire sits in a warehouse without ever touching a highway. Tragically much more is at stake, including the lives of unsuspecting drivers who may suffer a tread separation at 65 MPH with dire consequences. Even though the tread depth may look adequate in the appplication of the penny test with Lincoln's head, there's only one way to find the age of a tire. The code letters and numbers are mandated by federal regulations and can be found on the side of the tire and positioned just a mm or so from where the tire fits on the rim. For a start, make sure you see the letters D O T on the left end of the group. The numbers you want to look for are the last group on the right. The key to understanding is this: The four numbers shown below indicate this tire was made in week 42, year 2002.

The tire pictured below was made in week 34 of 2002 and easily passed the penny test but the cracks are a sure sign that this tire presents a potentially unsafe hazard, especially at highway speeds in the brutal Texas summer heat. From a normal walk-around visual inspection these small surface cracks in the photo below can hardly be noticed.

Now we come to a tire code with only three digits in the right-hand group of numbers. The key is this, three digits represent the 90's decade (pre-millenium) while four digits represent the 2000 decade (post-millenium).

Point to remember: 3 digits = years in the 1990's, 4 digits = years 2000 and up.

Also, use a tire guage at least once a month, keep tires at the pressure recommended by the car maker. See the sticker on the door post or gas cap door. Don't depend on a quick walk-around for a casual look-see to guess at appearance, but use a flashlight to look for surface cracks that could spell trouble down the road ahead. Acceptable shelf life can be a much as 12 years, depending on the dealer and tire maker. To protect yourself from being sold a tire that is too old, learn to decode those numbers. It may save you needless litigation and even your life.

Under average conditions tires can lose a pound of pressure every month and a pound for every 10oF drop in temperature. Underinflation causes heat build-up, a major enemy of tire life and safety.

This information came from an ABC news segment with Brian Ross, also courtesy of my local AAA approved Firestone facility which has given outstanding service for several years now. They allow a shelf life of only 5 years.

Safety First!!