Bob Rouleau

The OEM 997 GT3/RS tires are considered street tires and, compared to the "real" R compound Cups and Corsas, they are!

Best,

NJ-GT

I checked temperatures and grip levels from a recent track event with the RS.

My RS has full race-spec 265/30R19 MPSC, and OEM-spec 325/30R19 MPSC (7GT2 stock tires).

The OEM MPSC is a race compound tire. On the flat turns of the California Speedway infield, which are low speed turns (40-50mph), the RS generated higher g-forces consistently compared to my modified 996 GT3 on full monoballs/Motons and shaved 275/335 Toyo RA-1.

If my rear tires were a PS2 compound, when the tires heat up the car should go from neutral to oversteer, and this is not the case. The balance stays consistent. The grip level is consistently higher than shaved RA-1. The MPSC were generating 1.3-1.4 g at turn 4 and 5 (two 180s).

RonCT

My results were different. Compared same sized PS2s with same sized oem "cups" (235/305) - same handling characteristics, same cold / wet characteristics, same audible / tactile characteristics, same grip levels per TraqMate... While the RA1s in 245/305 (18" vs. 19) provided substantially improved grip levels and therefore lap times. Not sure what that all means, but the literature here at RL and even from Porsche says the OEM 19 "Cup" is not the same tire or compound as the normal Cup. I'm not a technician, so I don't know if some of this is related to set-up - but I've spent enough time on "real" cups in 18", RA1s, PS2s in 18 and 19", and the OEM 19 "Cups" and my findings jive with what so many others have posted here, including the people from Tire Rack.

mdrums

All I have to say is the 19" Michelin Sport Cups are EXPENSIVE!!!!

NJ-GT

Although it was on different cars, my fastest lap with the 996 GT3 on shaved RA-1 at California Speedway was a 1:52.3, while the fastest with the RS on MPSC last week was a 1:49.846. The g-forces generated by the MPSC were consistently higher everywhere compared to the 2004 GT3.

RS is on stock suspension other than rear toe links, upper dog bones and GMG sway bars. 2004 GT3 had Moton CS, front/rear toe links with bump steer adjustment, lowered 25/15mm, 750#/1000# springs when I ran Cal Speedway, full monoballs, 100 lbs ligther than the RS, Cup LSD and 4.00:1 R&P, PCCB and RS19 pads.

I've been running MPSC since 2003, I prefer the Toyo RA-1 (slower but versatile). Keep in mind that my front tires are full spec MPSC, while only the rears are OEM MPSC (325mm though). If there were a compound difference, it will show up after a few laps changing the car's balance, it did not happen, and I can't say I was not pushing the RS hard enough.