Tire Age – How old is too old?
Dec 22, 2022
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 age 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 Tire Age
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 1822 would mean the tire was made on the 18th week of 2022.
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.
Reputable tire shops may refuse to mount and install tires that are over 10 years old or show significant signs of aging. Although there are no federally mandated laws on tire age, tire and auto manufacturers agree that no properly maintained tire should be on the road after 10 years.
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 ages, the oils and binding chemicals dry out and loses flexibility. A tire’s ability to mould itself around the texture of the road is what makes it grip. Simply put, no flex, no grip. As the rubber oxidates, it becomes stiff and brittle, resulting in internal and external cracking under load.
The stiffening and cracking of aged rubber can lead to the inner layers of the tire delaminating from the steel belts rather than flexing with the steel as the tire rolls underweight. As tires age, not only does loss of traction occur, the tire is more likely to suffer complete structural failure (blowout).
Under ideal conditions, tires should be good for 5 – 7 years from date of manufacture and have a minimum of 6/32nds for winter and 4/32nds for summer. Tires older than 5 years should be checked on a regular basis for weathering, wear and age. For your safety and the safety of others, Tire Capital will not install or service tires older than 10 years – regardless of condition.
Heat, Sun and Extended Storage
Heat contributes to faster rubber oxidation. Exposure to sunlight and warm climates can make your tires age faster. When storing tires, keep in a cool, dry dark area. Tire storage bags are designed to keep harmful UV rays off the rubber and prolong life. Vehicles that may be parked for extended periods of time, such as RVs, trailers, etc., should use tire covers to protect from direct sunlight.
Tires kept in storage are not immune to the process of aging and rubber oxidation. 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.