NJ-GT

I like the RA1 much better than the MPSC. I ran MPSC for three years as my street/track tire, with awful results on autoX.

The RA1 is slower than the MPSC on dry/warm conditions. I would say, 0.3 secs per 60 secs lap. However, on cold weather, rain, autoX, street driving, the RA1 is much better than the MPSC. The RA1 lasts longer than the MPSC as well. I got 8,000 miles from one set of RA1 with around 8 autocrosses and 3-4 track days. No tire matches that.

The RA1 is the spec tire on the Speed World Challenge. It works with the heavy AWD Audi RS6, the C6 Z06, the 997 GT3 Cup, the Cadillac CTS, Volvo R, etc. In my opinion, if the tire is good enough for the 997 GT3 Cup, it's good for the street 997 GT3.

Just don't get mad when the guy with the 996 GT3 on MPSC is running faster lap times on a dry day.

frayed

The RA1s are reputed to handle heat cycles better than most rcomps, including the MPSCs. However, it's likely that the reformulated MPSCs we get stock on the 997 are better in this regard, since they were developed to be streetable.

grussell

Does anyone know the thickness of the spacers on the 997 GT3. Are they front and rear or just rear.

Also, why would Porsche use a 12" wheel for a 305? Wouldn't an 11" or 11.5" be better? Michelin recommends 10.5 - 11.5.

grussell

found it. I think it is 5mm spacers in the rear only.

so the perfect rear wheel might be 11.5" wide with 57mm offset?

03-turbo911

Yup, 5mm on the rear only.