Tires are a necessity for motorists, but it’s important to replace them before they get too tired. Arizona’s sizzling summers age tires even further, as is evidenced by the rising number of tire retreads, or alligators, strewn across Arizona roadways.

AAA projects that about 20,500 Arizona motorists will call for tire service this summer, with 2,750 to 3,000 of those expected from Tucson motorists. AAA tire experts want motorists to be aware of the danger of driving on old tires.

“Tires have an expiration date of about six years, even if they haven’t been used,” said Travis Mock, supervisor of AAA Owned Auto Repair for AAA Arizona. “Over time, heat causes tires to break down ingredients and polymers, causing them to become brittle.”

AAA tire experts offer these tips on buying tires:

  • Never buy used. Motorists may consider buying used tires to save a few bucks. However, AAA cautions against this, as you can’t be certain how the tires were treated before you acquired them. Plus, you could end up with tires that are 12 to 14 years old.
  • Save the date.
  • Every tire has a stamp that includes the date the tire was made. Look for a series of numbers inside a rectangular box on the sidewall of the tire. The last four numbers will be the manufacture date. For example, if the numbers are 0808, the tires were made in August 2008. AAA auto experts recommend not buying tires that are more than a year old.
  • Mile-mannered.
  • Tires often are advertised with a number that signifies how many miles the tire should last. Yet there are many variables that can lower that mileage, from the tires not being properly aligned to driving on rough roads. AAA auto experts say that number is more of a feel-good advertising number, and getting about 40,000 miles from a set of tires is fairly standard.
  • Rough ride.
  • Those higher-mile tires are going to be harder, with a thicker tread. And while harder tires last longer, they’re less comfortable and result in a noisier ride.
  • Pressure check.
  • You can find the proper pressure that your tires should be inflated to on your vehicle’s doorjamb — not the pressure listed on the tire itself. Even if you replace the tires with other models, the pressure should remain the same, because it is based on the weight of your vehicle. AAA auto experts recommend staying with the recommended tire for the vehicle and not to purchase other types, such as low-profile tires. The suspension and braking systems are designed to operate with a specific tire size, and other tires will change the steering and braking characteristics, which could result in poor performance.
  • Wear and tear.
  • Wear bars are located in every tire tread and look like a raised bump every few inches. Once a tire’s tread is level with those wear bars, it’s time to replace it. Another way to check is to take a penny or quarter and place it upside down in the tread. If the tread is up to the president’s forehead, it’s OK. Check tire pressure each month to help fuel economy, make tires last longer and optimize vehicle safety.
  • How low it can go.
  • If a tire looks low, it’s already more than halfway empty. In underinflated tires, the sidewall starts to collapse and the steel underneath the rubber will bend. When tires are inflated properly again, they tend to bulge and are prone to blowouts. Also don’t overinflate tires, to avoid abnormal tire wear.

Valerie Vinyard is a public-affairs specialist for AAA Arizona. Contact her at or at 258-0518.