CUP tires to track a regular 996 C2

[Dr. Carrera]

I can't wait to go back on the track with my C2 in a few weeks. In preparing myself I am considering to mount racing tires on a dedicated track-rim set: either Michelin Pilot Sport Cup or Pirelli P Zero Corsas.

By using those 'street-legal' racing tires, on, to and from the track, I aim not be restrained by the adherence and endurance limits by which my Conti SportContacts (and any road tire indeed I suppose) gave me a hard time on the track before.

My C2 is not fitted with the optional sports suspension and some people advise to give the car some more 'negative camber' in order to take full use of Cup tires.

Has anyone ever done this before? Any experiences to be shared would be welcome. :rolleyes:

P.S. I know I would be better off with purchasing a GT3 straight away. In fact, this will probably be my next one and my dealer even proposed me a nice 2nd hand Clubsport but the bank account advises me to wait 1 or 2 more years.

[clord]

Hi Doc..... "Has anyone done this before?".... Yes, it's a logical next step in enjoying your car on the track. Both the tires you show are street legal (DOT in the US), steel belted for normal resistance to street pot holes, etc, have track oriented rubber compounds, and reduced tread depths for minimum tread squirm on the track. With street suspension and alignment, you will wear the outer shoulders of the tires first in enthusiastic cornering.....and you may wish to bias your suspension setup toward more even tire wear on the track....but, it will compromise your street tire wear and handling....it's a compromise you must decide on and live with.

[Dr. Carrera]

Thanks for the feedback clord. You're right - it's a compromise to be chosen but I have to consider that this car's mainly my daily driver as well.

Upon looking into Tirerack technical recommendations for the PSC I found the following:

Vehicle Wheel Alignment Recommendations

Camber should be negative:

Acceptable 1 degree negative

Preferred 1.5 to 3 degrees negative (for most basically-stock or moderately-modified cars, the "sweet spot" is going to be in this range)

Maximum 4 degrees negative

Proceed carefully with camber adjustments. Too much camber means giving up efficiency in braking and accelerating. Achieving the right balance between cornering grip and straight-line grip (braking/accelerating) is key. For those enthusiasts who simply want the opportunity to explore their vehicles’ limits with higher levels of grip, but who don’t want to make serious modifications to achieve high negative camber values, Pilot Sport Cup will still operate effectively with more conservative factory settings for camber.

Caster should be set at the vehicle’s most positive recommended setting.

In most cases, toe should be set at the middle of the vehicle’s factory spec for each axle. However, depending on the competition situation (tight road course, more open, flowing road course, autocross, etc.) it is possible to materially affect the initial turn-in of the car and its stability in high-speed transitions through manipulation of the toe settings. Care must be taken because Pilot Sport Cup tires generate significant levels of lateral force even at very small slip angles; thus, large toe-out or toe-in settings can have big effects. In general, a good starting place is near zero toe (parallel) or the minimum value of the factory spec for toe-in at the front axle. At the rear axle, moderate toe-in (usually the minimum factory spec for toe-in) is not a bad place to start.

I am also curious about the statement: Pilot Sport Cup will still operate effectively with more conservative factory settings for camber. I assume this means effective yet not 100% optimal and implying uneven wear of tires.

Anyone know what is the factory camber setting on a '99 996 C2???

I don't have a clue what caster is about. I'll look it up in my Dutch-English dictionnary. :drive:

[ar38070]

Caster is not adjustable on a stock car so do not worry about it.

Max out the camber in the front. You will only be able to get 0.5 -1.0 with a stock suspension. You can leave the rear alone or perhaps increase it slightly to between 1.5 and 2.0.

Toe in front and rear should be 0 to 1/16".

You will wear your tires unevenly. Without some suspension changes there is not much you can do about it.

[Dr. Carrera]

Some people alert me that I should be worried about "oil starvation" due to pulling those high Gs with a wet sump? Is the difference in G-force between street tires and PSC or Corsa that big???

Clearly, my only aim would be to ensure adequate traction and me having fun on track-days. At the last one I attended with street tires, it was a stressful experience to feel the rubber melting away . Other than that I estimate to do not more than 3 or 4 track-days a year. For the remainder the car's is my daily driver.

[Scott in Houston]

If you experience oil starvation that means a combination of things.... 1) you've taken a long, high-G turn at crazy speeds

2) quit your day job, you're probably a better driver than most everyone out there.

No offense, but I'm guessing by the questions you're asking that neither will be true. :)

You shouldn't have to worry about the oil starvation issue. It's very rare and takes exceptional conditions to make it even possible including taking your car to 10/10th's which I hope you're not doing.

[GreigM]

I suppose in theory oil starvation is possible, and running semi-race tyres will only bring you closer to this theoretical problem - but in saying that I know of a 996 C2 which has been run on slicks with no adverse effects (yet) - but it may be something to be aware of.

As for tyres - The MPSC will give the ultimate grip, but only within a fairly narrow temperature band - they are hard to heat up especially on a cold day. They also offer absolutely no wet weather performance at all - if you are driving to/from the track be 100% sure it will not rain otherwise you will have an accident. They are also reputed to wear very quickly - some of the GT3 guys here in the UK are getting as little as 2 track days out of a set.

The Corsas are seen as a better compromise - almost as much grip as the MPSC (some people say just as much), better wet-weather performance (you can drive home in the rain, just take it easy) and a longer life. Also usually cheaper.

You might also want to consider Dunlop Super Sort Race (SSR) - a great compromise all round - much,much better than street tyres and some would say almost as good grip as the MPSC or Corsas, a lot longer life, almost as good as a street tyre in the wet and very cheap. A lot of people are running these tyres all the time - track, street, wet.

[Dr. Carrera]

thanks for the feedback guys

@Scott: you're right, I'm not quite driving at the levels of Schumacher. G-forces should be reasonable :D

@Greig: Considering the weather-conditions over here in Belgium (quite often rain and cold), similar to Scotland I guess, Corsa's may be more appropriate, and indeed, in the price offers I got, they are 150 EUR cheaper for the set of 4.