STLPCA

Dave
Although I've heard 5 yrs mentioned as a rule of thumb, the correct answer is "it depends." There is no magic time span. Tires naturally degrade over time ("shelf life") which is not the same as miles of use ("service life"). An unused tire will become unsafe to use if stored long enough. How long depends on the storage conditions.

Ideally tires should be stored vertically on a tire rack (not horizontally stacked) in a cool, dry, dark place without much air flow & away from electrical motors, oil, chemicals, sunlight, fluorescent or other bright lights. Virtually no auto tires are stored under ideal conditions. Obviously, tires mounted on a car will spend most of their time in poor storage environments so they, in essence, are wearing out even when the car is parked.

The primary problem is ozone which degrades rubber reducing flexibility and resilience & causing the rubber to crack (which may not be readily visible).

In short, if you've got tires more than a few years old, they should be regularly inspected for cracking, loss of flexibility, and other signs of aging.

BTW, ever check your spare tire for dry rot/cracking?

nile13

I think one more important factor is sunlight. If I understand correctly, rubber does not like UV. So the age of the tire is less of a measure than how long the tire has been exposed to the sun.
I personally have seen some mid-60s tires that still look perfectly OK.
The other thing that Dan mentioned is how exactly the tire is stored. Actually having the tires on the car that is on the ground causes deformation of the rubber very similar to flatspotting. Depends on the compound, but usually it's an irreversible process.

lexpilot

Rob 993,
Sorry to be late responding. We're on vacation and I did not get online for the last 1.6 days.
The 265/40-17 do not look outsize on these Turbo Twist's. The P.O. installed them and I did not realize they were oversize until a month after I owned the car. They do not appear to be wearing abnormally across the face width. I am not entirely sure what the rim width is front and rear as these wheels were not available as a 1995 option to the best of my knowledge. Experts ?
The biggest tire retailer in the Pacific Northwest is Les Schwab. They have the most number of towns for location and their service is the best I have experienced. They are not the cheapest supplier, however. Their major brand is Toyo for their full line up. So in Oregon they are the best choice for a unique tire size, etc.
I had a problem with one of my valve stems recently and they promptly replaced it and were very careful with my Pcar. I run big fat Michelins on my Duramax and they have been careful with my expensive Weld alloy wheels on it, too.

Rob993

Thanks Lexpilot! I have the factory 17" cup tires and I am pretty sure they are 9" on the rear and 7" on the front. The wide grip looks great on the p-cars so I would love to squeeze a 265 if possible. (my front tires have lots of life still).

Right now I have 255/40-17 on the rear and 225/40-17 on the front. Any suggestions will be very much appreciated.
Thank you
Rob

Rob993

Edward, I am sorry that I hi-jacked the thread for some of my own questions. I will get the hang of this thing sooner or later.

Thanks
Rob

Dudley

Thanks Dan, Mike.

graham_mitchell

I had another look at that list of sizes for the PS2 tires which I posted. I can see already that it is missing some sizes. I just copied and pasted from a reseller's website.

I contacted Michelin directly to try and get a definitive list. I will post the results. Sorry for the confusion this may have caused!