I picked up a nail in my rear passenger side tire and had it replaced. Porsche dealer said other 3 tires were new enough and only needed to replace the damaged tire. All 4 tires are Michelin Sport Cups, the rear right tire is just newer.

Now i I have noticed the car pulls right under hard acceleration. It seems to go straight when cruising, coasting braking, but goes right when flooring it to the point I have to steer slightly left to stay in my lane.

Is this normal or anything to worry about? I was hoping after driving and tracking the car, this will break in the new tire enough to straighten it out. Anyone experienced this before?

Could this cause any damage to the diff or anything?

 

How many miles on the new tire? A new tire takes some time to "break in" mainly heat up a few times to lose the mold release compound that can make a new tire a bit slippery. I don't recall any specifics but I generally take it easy so to speak on new tires for a few hundred miles. Nothing super special. I just drive the car like I usually do which mainly consists of approx. 30 miles to work then back again to home. Most of these 30 miles are at freeway speeds.

By the numbers...

Are tire inflation pressures all Ok? Not just the new tire but the other 3?

Is the new tire the *same* as the other rear tire? Same brand, model, size? You have to get down and write down the details from the other rear tire then the new one. Right down to the tread hardness number and the date code. The new tire probably has a newer date code but maybe not. It could be a much older date code. Anyhow, get details of both tires down on paper. If you need help decoding the info post it here and someone will help you.

Also, if the tire is unidirection is it (and the other 3) mounted in the right direction?

How "new" is the other tire on the "axle"? Porsche says the other tire on an "axle" should be replaced if the tread wear of the other tire is 30% from new. To put this into perspective I manage around 20K miles on the rear tires of both my Boxster and my 996 Turbo. Thus 30% wear represents around 6000 miles. Some owners get half that 20K or even less around 8K miles. If you fall into this category then at 2400 miles the other tire has 30% tread wear and should be replaced.

To take the guesswork out of the picture the tech should have used a tread depth gage to check the other tire's tread depth and then advised you regarding if the other tire needed replacement.

 

Not sure if it's the same on the GT3 but I know on other marques (Ferrari for example) if you have to replace one rear tire they want you to replace both at the same time for the reasons you mentioned experiencing. Maybe there is something in the manual about it?

 

Experienced the same thing on my 2011 GT3. I went ahead and replaced the other tire and everything was fine.

 

Was the difference in tread depth between the new tire and the old one on the other side 30% or greater?

'course, even if the tread depth difference was less than 30% can't argue with the results.

 

Didn't measure the tread depth. But as you stated, the results seemed to prove enough. This is one of those things that made me realize how sensitive these cars are, and not to mess with too much.

 

I appreciate all the tips. I had the dealer go ahead and replace the rear driver side tire as well. The car now goes perfectly straight when accelerating or coasting.