My 5 month old rear Pzero Asimmetricos are developing cracks in the inner sidewalls and will have to be replaced. I guess the heat from the turbos cooked them. Will 305 or 315/30-18 Pzero Rosso's fit without rubbing the bodywork or suspension? They are 25.2 and 25.4" diameter respectively. The front 225's are 25.2" tall so the diameter should be compatible. I'm hoping the Rosso's will be quieter, less harsh riding and more durable than the Asimmetricos. I'll be using the stock 11" wheels.

 

Your front tires *were* that tall... If they're significantly worn,
they are now shorter. The cracks are from age, mostly, though
heat might have contributed. The tires were new to you, but it
is *possible* the tires had been on the shelf too long. I'm
guessing we'd have all heard more stories about the turbos
killing our tires if it was a common thing. There is probably some
big long build number on the tires that Pirelli can decipher for
you, and tell you when they were made.
If you are switching all four tires, then have at it, as long
as the diameters are very close. Wider tires *can* rub the inner
fenderwell walls in the rear.
If your front tires are nearly new then it should be OK to just
get rears, but I would feel a little funny running different tire
models front to back. I *have* done so, in fact at one time I
raced Hoosiers with roadrace compound in the front, and in the
rear I ran autocross compound, because at that time Hoosier
didn't make the fronts in my size in the autocross compound...
Joe

 

Joe,
Duane has had some problems with abnormal wear and blowouts. I originally thought it was an excessive negative camber problem, but now I am beginning to wonder.

Here is the thread relating to Duane's issues:

https://www.6speedonline.com/forums/...hlight=blowout

Now, when you see how hot the turbos become, you have to wonder. Take a look at this (you have to press play):

http://mluni.com/ml/FLASH/kpv/DynoDay.asp

 

I guess it may have to do with a non-standard wheel, and maybe
the offset and tire width *is* putting his tire too near the turbo.
Especially if those tirewall cracks are only on the inside of the
rear tires, and he's been feeding it fresh tires like popcorn...
This should be chalked up as another caution about venturing
away from stock specs in wheel and tire sizes.

 

I do not believe the turbo's contribute to the tire problem. My turbo's are extremely close to my tires. Maybe 1/8 to 3/16ths of an inch. I have no tire problems.

 

I tend to agree Chad, however I am not totally sold on the idea that heat soak, of the the tires that is, is not a little at fault. I was mentioning the other points to spark a debate and of course shoe horn the video in. LOL

I guess one can argue that after the turbos have undergone heavy use and heated up substantially, a stopped car will allow one area of the tire to "cook". I wonder what the actual delta T would be simply due to convection.

 

I found out the tires were installed at the Dallas Porsche dealer a couple of days before I bought the car. It's possible they sat on the shelf for a while. I don't think that 295 size Pzero's were made before mid 2001 (?). I worry that Pirelli may have compromised the rubber compound's heat and ozone resistance while trying to obtain maximum traction. I drove the car to work daily this summer with idling at stoplights. We had many 100 degree high ozone days. The cracks are located only on the inner sidewalls.

 

Tires were made in the 10th and 15th week of 2001, so age is a factor. Keep an eye on Asimetricos over 3 years old.