Crack the code: How old are your tires?

The last four digits of the DOT number represent the week & year of the tire's manufacture (this example: 43rd week of 2009)
The last four digits of the DOT number represent the week & year of the tire's manufacture (this example: 43rd week of 2009)

MONTGOMERY, AL (WSFA) - Your tires may be the most important pieces of safety equipment on your vehicle. If they're not in good condition, you're just waiting for an accident to happen.

But the old trick of checking your tread depth with a coin isn't enough anymore. Now, manufacturers say the age of your tire is just as important.

"A tire is like any other product," explained attorney Rick Morrison of the Beasley-Allen law firm. "Over time, it's going to deteriorate. It's going to wear out."

Morrison showed us a tire, which by all accounts, looked brand new when it was installed on his client's car. But he says it was actually 10 years old.

"72 hours later it failed and caused a rollover wreck," he said. "And a little girl is now paralyzed."

The problem is oxidation -- air, heat, and sunlight all cause the rubber in tires to break down. That's why car companies now suggest never driving on tires older than 6 years. Some tire manufacturers give a slightly longer window, recommending that tires be replaced before 10 years.

[WEB EXTRA: Read more from Consumer Reports]

WSFA 12 News went undercover to check the age of tires for sale at local stores. None of the tires we found were past the 6-year mark, but we did find tires as old as 3 years. That means that the moment it's installed, you've already lost 3 years of the tire's life.

And when it comes to our hidden camera investigation, remember that many shops keep their tires in the back and out of the view of our cameras.

That's why it's important to check your tires' date of manufacture.

How to find the date your tire was made:

Look for the "DOT" number. It's a long series of numbers and letters on one side of the tire. Then look for the last four digits, which represent the week and year of manufacture.

For example, if the last four digits of the "DOT" number are 2314, then the tire was made in the 23rd week of 2014.

If it's older than 6 years, replace it.

"The tire can look brand new. It may never have been used," Morrison told us. "Get it off the vehicle."

It's also important to do basic maintenance on your tires. You should check the tread depth and air pressure regularly. And rotate the tires when necessary.

More safety tips:

  • A tire is considered bald if it has 1/16th of an inch or less of tread depth. Most tires have built-in treadwear indicators that let a motorist know when they should be replaced. The indicators are raised sections spaced intermittently in the bottom of the tread grooves. When they appear even with the outside of the tread, it's time for new tires.
  • Use a Lincoln penny as an easy way to check for tread condition. Just place the penny upside down within the tread, with Lincoln's head facing downward. If you can see the top of Lincoln's head, the tires need to be replaced.
  • Bald tires are also between 1.5 and 1.8 times more likely to be under-inflated than tires with deeper tread. Make sure you are using an accurate gauge to test tire inflation.
  • The NHTSA found that almost 20 percent of gas station tire-pressure gauges over-report the pressure by at least 4 psi or more. It's better to keep and use your own gauge, which has been tested and certified as accurate.
  • Do not rely on a visual inspection to determine whether a tire is properly inflated. Always use a reliable gauge. Proper tire inflation guidelines can be found in your automobile's owner's manual or on a placard in the glove compartment or driver's doorjamb.
  • If your tires are more than six years old, you may want to consider replacing them. As tires age, the rubber can become more brittle and more prone to a blowout.