Are you familiar with the horrific accident that killed the actor Paul Walker in 2013. It has been revealed that the Porsche Carrera GT in which he was riding had nine-year-old tires. Is this important? The California Highway Patrol noted that the tires’ age might have played a factor in the accident.

What can tires expire? For years, people have relied on the tread depth to judge a tire’s useful condition. If there is still tread left, then the tire’s still good is the popular belief. But the rubber compounds deteriorate with time. An old tire is quite capable of being a safety hazard. For most of us, old tires will never be an issue but if you only drive 6,000 miles a year, aging tires could be a serious issue.

Want an example? Everyone knows that rubber bands age poorly. They get brittle and develop cracks within a few years. That’s essentially what happens to a tire. Cracks in the rubber begin to develop over time. This aging can eventually cause the steel belts in the tread to separate from the rest of the tire.

So how do you determine the age of a tire? Tires made after the year 2000 have a four-digit DOT code that is embossed on the sidewall. The first two numbers represent the week in which the tire was made. The second two represent the year. Example: a tire with a DOT code of 0908 was made in the 9th week of the year 2008.

So how long does a tire last? The guys at Reedman Toll Subaru explain that the National Highway Traffic Safety Administration (NHTSA) has no specific guidelines on tire aging. Some tire manufacturers, such as Continental and Michelin, say a tire can last up to 10 years but many manufacturers say less age is more prudent.

In summary, of all your vehicle’s components, it’s tires have a huge effect on the way it handles and brakes. So keep your eyes on your tires, if you only drive a small amount every year, you may want to replace your tires before the tread is actually worn down.