Tires and age

My late uncle was an engineer for one of the big tire companies. I once asked him about the "6 years maximum life" rule. He responded that yes, that was an often quoted manufacturer's guideline and it was mostly concerned with UV exposure. He also said, "You have to remember that the guidline is aimed at the general public, and that the manufacturers always assume the worst case consumer situation. When it comes to UV exposure that means tires on a car that is never garaged and lives in a sunny climate. If you do the math on how many hours of UV that might add up to in six years, I would think that our cars would have only a tiny percentage of the exposure. Still, of course, newer has to be better.

 

I finally rotated the spare out of the trunk after about 7-8 years. Obviously, it was in total darkness for that entire time. It lasted just a little over a year and about 20K miles vs. the 40K I was getting from fresh tires.

 

The problem, to my mind, is not so much fear that the tire will catastrophically fail; rather, the concern is that its grip and performance will become subpar over time.

The tires on F-cars use a softer rubber compound for better grip, and over time the compound hardens, causing less grip.

 

from my experience tire life depends on a lot of variables .. if the car is garage kept particularly in climate control and then only driven on sunny weekends 20 or 30 miles at a time they will last for a very long time.. sure they will not have the same grip but then in this case the cars are not being driven hard.. On the other hand if the car taken out for 50 to 100 mile drives or longer at high speed then it would be wise to replace them after around the 6 year mark maybe a little longer.. High speed on hot roads will make the tire heat up which will put the tire closer to its limits ... so need to be extra safe then...tires are expensive to throw away for no reason on cars that are barely driven...I am speaking mainly of classic cars...