Can burnouts structurally weaken tires??

"Over 5 years old no matter the mileage should not be driven at hi-way speeds". This is not necessarily true.

From an article at Edmunds.com:

How Long Does a Tire Last?
Carmakers, tiremakers and rubber manufacturers differ in their opinions about the lifespan of a tire. The National Highway Traffic Safety Administration (NHTSA) has no specific guidelines on tire aging and defers to the recommendations of carmakers and tire manufacturers.

Many automakers, including Ford, Nissan and Mercedes-Benz, tell owners 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 said there is no way to put a date on when a tire "expires" because such factors as heat, storage, underinflation and conditions of use can dramatically reduce the life of a tire. Here's more on each of these factors:

Heat: NHTSA research has found that tires age more quickly in warmer climates. NHTSA also found that environmental conditions, such as exposure to sunlight and coastal climates, can hasten the aging process. People who live in coastal states and other areas with warm weather 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. 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.

Spares: They usually don't see the light of day, but they're still degrading with time. If the tire has been inflated and mounted on a wheel, it is considered to be "in service," even if it's never been used. And if a truck's spare is mounted underneath the vehicle, it's exposed to heat, dirt and weather — all reasons to plan on replacement.

Conditions of use: This refers to how the tire is treated. Is it properly inflated? Underinflation causes more tire wear. 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 age differently from 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. It is important to maintain proper air pressure in tires, rotate them regularly and get routine inspections.


How to Determine the Age of a Tire
The sidewall of a tire is covered in numbers and letters. They all mean something, but deciphering them can be a challenge. This Edmunds article about reading a tire's sidewall goes into greater detail. But to determine the age of a tire, you simply need to know its U.S. Department of Transportation (DOT) number.

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 1116 was made in the 11th week of 2016.

Tires made before 2000 have a three-digit code that is trickier to decode. The first two digits still indicate the week, but the third digit tells you the year in the decade that the tire was created. The hard part is knowing 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. Really, you can ignore all that: If you see a DOT number ending in three digits, the tire was made in the last century and needs to be replaced as soon as possible.

Clearly, these DOT numbers weren't designed with everyday buyers 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 full 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.

After checking out a tire's birthdate, give the rubber a visual inspection. Some of the best advice on such an inspection comes from the British Tyre Manufacturers' Association. 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 said. It recommends replacing the tire immediately if such symptoms appear.