Tire age is an often-overlooked factor that can drastically affect driving safety. Drivers usually gauge the life of their tires by the amount of tread it has left, rarely taking into account the effect age has on them. Just because your tires have tread left doesn’t mean they are safe.
For daily drivers and work vehicles, tire tread tends to wear out long before age compromises their performance. For classic cars, show cars, and weekend drivers, tires are much more likely to reach an unsafe sage before the tread wears out. Tires that are kept in storage for an extended period and spare tires are also more likely to succumb to the effects of aging.
How to identify the age of a tire
The manufacture date is on the sidewall of a tire. Locate the four-digit number after the visible DOT (Department of Transportation) designation. The number shows as a week and year. For example, a DOT number of 0820 would mean the tire was made on the 8th week of 2020.
If you check the DOT number and it only has three digits, the tire was manufactured before the year 2000. If you have a tire of this age on any vehicle, replace it as soon as possible.
How long can a tire last?
Most auto manufacturers recommend replacing tires over six years old regardless of tread depth. Some tire manufacturers like Michelin and Continental give a 10-year limit.
As rubber compounds age, they deteriorate and become weaker like other rubber and plastic components on your car. This process is called rubber oxidation, which dries out the compound. As the rubber oxidates, it becomes stiff and brittle, resulting in internal and external cracking under load.
There is no mandated rule on tire age, but the older they are, the more dangerous they become. Several factors can shorten a tire’s life while it is in storage or off the road.
Exposure to heat
Heat contributes to faster rubber oxidation. Exposure to sunlight and warm climates can make your tires age faster.
Tires kept in storage are not immune to the process of aging and rubber oxidation. Storage spaces without climate control like a garage or shed will cause tires to oxidize and breakdown due to the effects of heat.
Even if a tire is stored in an environment that protects it from extreme temperatures, the rubber compound will still breakdown over time. A tire stored inflated on a wheel will succumb to oxidation faster than one stored unmounted.
Remember, a tire that has been in storage for years may look completely fine, but the effects of time will still impede its performance.
Summer and weekend car tires
If you have a vehicle that sees the road less than your daily driver, you may hit the tire age limit before they wear out. The temperature and storage factors from above also come in to play on summer and weekend vehicles. Check the age and condition of the tires on your summer or weekend vehicle whenever you take it out of storage for the season.
Spare tires are rarely thought about unless you get a flat, but they are exposed to poor storage conditions. Spares mounted beneath a truck or SUV are continually exposed to road salts, oil, dirt, and temperature fluctuations. Spare tires kept inside a car are baked by the sun and frozen in the winter.
Tire damage and care
A tire that has been patched, over or underinflated, or has not been rotated will age faster. Tires that are cared for will have a longer life than those that are not.
So are my tires too old?
It depends. Generally, a tire over 6 years old will not be as safe or effective as it was new. However, factors like temperature exposure, care, storage, and use can increase or decrease the amount of time a tire can be used before being retired.
The DOT tire age designation will tell you when a tire was manufactured. The DOT designation is particularly useful when buying tires from a non-dealer, or inspecting the tires on a classic/weekend/summer vehicle.
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