[ds968]

I don't have a temperature gauge, so not sure if this question can be answered without some real temp numbers behind it, but will try anyway ..

I went out for a spirited drive today with a friend of mine who has a 2010 911. We both have the same tires ( Michelin PS 2 ) on our cars and after a 30 minute twisty roads drive when we stopped for breakfast he decided to check the temps of the tries by touch . Hie tires were warm to the touch, mine were ice cold. I thought his might be underinflated so we checked both and we had similar PSIs , but there was a very distinct difference to the touch . Also, both tires have similar mileage on them , but there is a huge age difference : his are about two years old, mine are going on maybe six or seven years old.

So does age make a difference in tire temps ? Or is it just a matter of the difference in traction and how a 911 affects the tires vs how a 968 does that ? Or a combination of both of those things ?

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[Rap]

Why are you driving on tires that old? I want to be a beneficiary on one of your life insurance policies. Please make the change tomorrow.

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[ds968]

Probably because I don't keep some kind of calendar system to remind me when it's time to change any given thing on cars.. really bad habit, I know ...


Ugh, I just checked ; seven years and eight months old. Ok, better get new ones, that's pretty old even by my car-neglect standards. Michelin claims their tires are safe up to 10 years . Same claim by Continental . Other manufacturers claim six to eight years max. But I think they're referring to the shelf life before installed and filled with air which changes the dynamics completely. Pretty much the same as Gates indication re the safe self life of their timing and balance belts being six years before they're installed in a car . After which you can still put 60 K miles on them . Yeah, we all know how reliable THAT assertion is ! And when I say " we " I mean ME. Timing belt busting costs only $ 5 K , If my tires bust while driving , particularly the way I do the six speed , the result might not be that inexpensive ..

I suppose tire longevity also depends a lot on where you live , in Phoenix the summers will probably kill your tires in three years, in N Dakota the winters will do that , but here I'm guessing the lifespan is at least double .

Update : I just spoke to my friend - he's pretty sure his tires are from 2009 also . The PO took delivery of the car in late 09, and there's record of the tires ever having been changed .


So back to the temps : maybe a difference in 911 vs 968 dynamics , but wouldn't an older tire get hotter a lot faster ?

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[flash]

lots of things at play here.  camber angle, corner loading, cold pressure, etc.

 

if he started under-inflated, he may have ended up the same as you if you didn't.  an under-inflated tire will heat up more quickly, and develop more pressure as a result.  he could start at 30, and you at 36, and both of you end up at 40, depending on how much camber, the weight on that tire, etc.

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