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Tire Aging

Most vehicle owners can easily overlook tire aging, increasing their risk of a crash. These Q&As will help you understand tire aging, how to extend their service life, and when to replace your tires.

What is it?
Tire aging occurs when the rubber and other components in a tire change over time due to service, storage, and environmental conditions.
Am I at risk?

Most of us drive our vehicles enough that the tires’ treads wear out, and we replace our tires before aging becomes an issue. However, if you own or use recreational vehicles, 15-passenger vans, collector cars, any other vehicles you don’t drive regularly, or if your annual mileage is low, you could be at risk. 

In addition to infrequent use, exposure to sunlight and warmer climate, poor storage and poor maintenance also contribute to tire aging. Tire aging is a greater concern in the more southern parts of the Sun Belt states, as illustrated in the map on the right.

What can I do?
You cannot detect tire aging simply by looking at your tires. However, there are steps you can take to extend the service life of your tires.

    Tire Pressure Maintenance Symbol (TPM)
  • Conduct monthly maintenance inspections, focusing on proper tire inflation pressure, treadwear and tire damage, along with recurring tire rotation, and balancing and alignment services.
  • If your car has a Tire Pressure Monitoring System (TPMS), pay attention to it! All passenger cars, light trucks, and vans that are model year 2008 or newer come equipped with this feature. If the TPMS symbol lights up on your dashboard, it means at least one tire is already significantly underinflated—you should take immediate action.


When should I replace my tires?

    Tire tread penny test
  • You should stop using tires for several reasons, including if a tire’s tread is worn down to a minimum depth using the penny test, signs of physical damage (cuts, cracks, bulges, etc.), or signs of irregular wear or other damage due to under inflation or overloading. Don’t use your spare as a replacement for worn tires.
  • Consumers are strongly encouraged to be aware of not only their tires’ visual condition but also any change in how they perform. If you notice any tire performance issues, such as failing to maintain proper tire inflation pressure, noise, or vibration, consult a tire service professional.
    DOT Tire Identification Number (TIN) with 4-digit Manufacturer Code
    DOT Tire Identification Number (TIN) with 6-digit Manufacturer Code
  • As tires age, they are more prone to failure. Some vehicle and tire manufacturers recommend replacing tires that are six to 10 years old, regardless of treadwear. You can determine how old your tire is by looking on the sidewall for your DOT Tire Identification Number (TIN) . The last four digits of the TIN indicate the week and year the tire was made. If the TIN reads 0308 it was made in the third week of 2008. Look on both sides of the tire. The TIN may not be on both sides.
Be aware of your spare
Spare tires on all vehicles are prone to aging because they seldom get replaced. Taking into account that tires degrade over time, NHTSA recommends that if your vehicle comes equipped with a full-size spare tire, that it not be used as a replacement for worn tires, except in emergencies such as replacing a flat tire.