1. Business

Consider age of tire in addition to wear

In Rick Stroud's auto shop, there's a pile of about 25 tires he doesn't know what to do with. They've never been used before, but are now considered worthless. Because the tires have been sitting in his shop for years, they've begun cracking and are no longer in good enough condition for the road.

"We see tires that are more than 6 years old, even if they've never been used, develop dry rot," said Stroud, owner of Rick Stroud Tire & Auto Service in St. Petersburg. "They may still have a lot of tread, but they're not in good shape."

Instead of stocking his shop with tires, Stroud now has them delivered twice a day based on sales.

Aging tires — or old tires that have never been used, such as the ones in Stroud's shop — can cause safety issues on the road, even deaths. Old tires that look new can be made unsafe by infrequent driving. A tire that is 6 to 10 years old, even with good tread, can develop cracks on the surface or inside the rubber compounds and bust open on the highway in extreme cases.

A driver who drives 12,000 or more miles a year will become aware that their tires are getting old because the tread will look worn.

Many manufacturers estimate tires can last for five to 10 years, but Stroud said that depends on the conditions they have been exposed to.

"Up north, you can have a tire last seven or eight years," he said. "But in Florida, with extreme conditions, a tire may only last three or four years."

The National Highway Traffic Safety Administration has noted in the past that tires can age quicker in hotter conditions and more sunlight.

Fortunately, there are ways to determine a tire's age. Each tire is required to have a U.S. Department of Transportation (DOT) number stamped into either the front or back of the tire.

For example, if the number 4112 is stamped, it means the tire was made during the 41st week of 2012. If the number is on the back of the tire, you may have to take the tire off to see the date. Keep the DOT number in mind next time you are at an auto shop for service or getting your tires rotated.

If you're buying new tires from a tire dealership or an auto shop, ask how old the tires are and look for the DOT number. There have been cases where people have been scammed into thinking they bought brand new tires, only to find out later the tires are a few years old but have never been driven.