For some people, old tires might never be an issue
by：Tanco Tire,Timax Tyre 2020-11-03
That's essentially what happens to a tire that's put on a vehicle and driven. Cracks in the rubber begin to develop over time. They may appear on the surface and inside the tire as well. This cracking can eventually cause the steel belts in the tread to separate from the rest of the tire. Every tire that's on the road long enough will succumb to age. Tires that are rated for higher mileage have 'anti-oxidant' chemical compounds built into the rubber that will slow the aging process, but nothing stops the effects of time on rubber, says Doug Garvin, Michelin's director of product marketing for passenger cars and light trucks.
How Long Does a Tire Last?
Carmakers, tire makers and rubber manufacturers differ in their opinions about the lifespan of a tire. Mercedes-Benz tell consumers to replace tires six years after their production date, regardless of tread life. Tire manufacturers such as Continental and Michelin say a tire can last up to 10 years provided you get annual tire inspections after the fifth year. The Rubber Manufacturers Association says there is no way to put a date on when a tire 'expires,' because such factors as heat, storage and conditions of use can dramatically reduce the life of a tire.
Heat: It has found that tires age more quickly in warmer climates. It also found that environmental conditions like exposure to sunlight and coastal climates can hasten the aging process. People who live in warm weather and coastal states should keep this in mind when deciding whether they should retire a tire.
Storage: This applies to spare tires and tires that are sitting in a garage or shop. Consider how a spare tire lives its life. If you own a truck, the spare may be mounted underneath the vehicle, exposed to the dirt and the elements.
A tire that has not been mounted and is just sitting in a tire shop or your garage will age more slowly than one that has been put into service on a car. But it ages nonetheless.
Conditions of use: This refers to how the tire is treated. Is it properly inflated? Has it hit the curb too many times? Has it ever been repaired for a puncture? Tires on a car that's only driven on the weekends will have a different aging pattern than those on a car that's driven daily on the highway. All these factors contribute to how quickly or slowly a tire wears out. Proper maintenance is the best thing a person can do to ensure a long tire life. Garvin recommends that you maintain proper air pressure in tires, have them rotated regularly and have them routinely inspected.
How To Determine the Age of a Tire
The sidewall of a tire is littered with numbers and letters. They all mean something, but deciphering them can be a challenge. Tires made after 2000 have a four-digit DOT code. The first two numbers represent the week in which the tire was made. The second two represent the year. A tire with a DOT code of 1109 was made in the 11th week of 2009. Tires with a three-digit code were made prior to 2000 and are trickier to decode. The first two digits still tell you the week, but the third digit tells you the year in the decade that it was created. The hard part knows what decade that was. Some tires made in the 1990s - but not all - have a triangle after the DOT code, denoting that decade. But for tires without that, a code of '328' could be from the 32nd week of 1988 - or 1978.
Clearly, these DOT numbers weren't designed with the consumer in mind. They were originally put on tires to make it easier for NHTSA to recall tires and keep track of their manufacturing date.
To make matters worse, you might not always find the DOT number on the outer side of the tire. Because of the way a tire is made, it is actually safer for the technician operating the mold to imprint information on the inner side of the tire, so some manufacturers will opt to put the number there. It is still possible to check the DOT code, but you might have to jack the car up to see it. Keep the visibility of the DOT number in mind the next time you are at a tire shop and the installer asks if you want the tires to be mounted with the raised lettering facing in.
That potential inconvenience is going away, however. After checking out a tire's birth date, give the rubber a visual inspection. It recommends that consumers check tires regularly for any sign of aging, such as tread distortion or large or small hairline cracks in the sidewall. Vibrations or a change in the dynamic properties of the tire could also be an indicator of aging problems, the association says. It recommends replacing the tire immediately if such symptoms appear.