I tried a search and didn't get much. (Well, I got a ton, but no answer.) It seems that there were several different makes of tires put on the factory Turbo Twists. (Michelin, Pirelli, ...) I remember reading an article where a Porsche engineer stated that they designed the car's handling around a specific tire compound, so I'm a little confused as to how multiple manufacturers could have provided tires to the factory. Lastly, and easiest, what are the factory tire sizes? Thanks.
-Seth

 

I think my car came with Pirellis.

http://www.seriouswheels.com/cars/to...-911-Turbo.htm

 

mine came with Bridgestone SO2s on GT3 rims. Tire size 225/40ZR 18, 295/30 ZR 18.

Porsche tires use an N rating...and I read the same articles about the N designation designed specifically for Porsche...LOL

 

This MAY be true, but is often simply that Porsche and a mfg come to an agreement on a particular tire meeting their spec (could be compound, construction or just tred grooves... or no difference at all), the mfg agrees to meet that spec without making changes to the tire without Porsche approval and gets to call it an Nx spec tire. Guaranteed sales to people that are less price conscious- or more **** about 'it needs to be a porsche tire'- or scared to make a mistake.

There ARE tires that are not suitable for any particular car- BUT, there are plenty of tires every bit as good as a Porsche rated tire, or better.

225/40-18 295/30-18 are factory sizes for the 996tt

235/40-18 315/30-18 are factoru sizes for the 996/GT2