AW, Thank you for the input I should have given a better description of my car. It is a highly modified GT car designed for SCCA GT 2 it is mostly tube frame with a 993 rear suspension and all the ERP adjustable links and a 935 front suspension. All carbon fiber or composite body panels including the roof. triple adjustable JRZ dampers, regeared G50, race motor, etc. SCCA rules state a max tire cross section width of 12" up front and 13.75" in the rear. The car will weight around 2,220-2280 lbs with driver.
The car is capable of being set up for slicks and the cost per set is not a concern.

That said what do you guys think would be the best tire to start with on my car, Michelin, Dunlops, or brand X.

Thanks in advance for your advice.

 

I think I would start with some Michelin S7A (soft) front and S8A (medium) rear. You can probably use the GT3 Cup user manual car allignment setup specifications as a starting point. Let me know if you need that data.

That sounds like a killer car. any pic?

AW

 

In PRC's GTL class we run a Goodyear R600 bias-ply slicks (23.5x10x16 and 25x12x16) in an R600 compound. They were selected for longevity not stickiness. It was hoped that we would get 3 race weekends out of a set (about 18 heat cycles) and that looks like it will occur. I've got about 17 cycles on my first set and they are doing fine. They were just flipped on the rims in the rear to even out the wear and help them to last another weekend. It appears that -1.5 front and -1.0 rear are good starting points for these tires on 2100-2500 lb cars (all 911's).

 

AW, I will post some pictures some time next week if you would like.

Tom W I am running 18" wheels and as far as I know Goodyear does not make a Biasply tire in that size. Otherwise I might be tempted to try them.

 

I have tried to post some photos but I am unable to resize them. I have posted a thread on pelican with photo's " My race car is finally finished"

 

Well it happened to me...I ordered a couple sets of rear "Cup" tires and was sent one set of 9A's. Anyone ever figure out what's going on with these tires? My concern is that the 9A's don't have the same sidewall construction as the Yellow "Cup" tire, so will be slower.

Also, I think the other set I received didn't have any markings at all (will check tonight). I ran those this weekend, they seemed to be fast like a Cup tire.

 

I called around and here are some of the things I was told. I spoke with Michelin vendors J3 and Sube Sport and two folks from the Michelin supplier JD Motorsport including Bob Williams who does race support:

The S9A is the same as the Cup tire. This is from Bob Williams who asked Michelin back in France. He also says that the S8B front tire is the Cup tire. J3 confirmed that some random tires will not get the "Porsche Cup" stamp, but they are the same. Someone else at JD suggested that Michelin will be labeling yellow Cup tires in S8B/S9A, so as not to be confused with the new blue Cup tires which will say "Porsche Cup".

I asked Bob what compounds the Cup tires were and he admitted that he couldn't really say. Whether a tire was "soft", "medium", or "hard" didn't just depend on the rubber but tire construction. He says its complicated and he's seen different things on the track. Folks at Sube Sport said the Cups are soft front/intermediate rear. As an aside, I had to run a set of S7A fronts with Cup rears since the front Cup are not in stock in the States currently. I honestly can't say that I noticed any difference in performance, we'll see how the fronts hold up, so far with three heat cycles they seem okay. This was on a faster track with low 70 degree temp. In my mind, if the rears are a hard compound the car would have oversteered. Preliminarily confirmed to me that the Cups are soft/medium.

 

No, as we posted before the cups are medium front and hard rear.

7= soft
8 = med
9=hard

The yellow CUP tires are 8 front and 9 rear. The cheaper tires are 7 front and 8 rear.
Not sure about the blue ones.

 

I just read the firs post of the thread. I am writing from Italy and I don't know if things are different overhere.
Anyway: the right compound for a 997 gt3 cup is now the 282G, and there is a blue sticker on the tire with the writing Porsche Cup. this is the 24/64x18 front.
THe rear best compound is now the 331C and the Porsche Cup sticker is in green color.
The 2 colors should identify the national carrera cup tires from the world Supercup tires.