333pg333

I'm going to slicks very soon but am getting mixed messages as how many heat cycles you can achieve with these. Obviously a lot of variables come into play but from what I can gather 8-12 heat cycles are possible as an approximation. I am not talking about Hoosier R6 / BFG R-1 type DOTs. I'm talking about proper race slicks.

My car is a modified 951 weighing about 3100 with me and fuel. We run short sprint races. 4-6 laps 3 or 4 times in a day. We do qualifying in the morning for speed groups. I could even do this on some R specs to save the tires? The qualifying isn't that important as strange as that may seem to you guys.

Of course compound vs longevity is probably the main issue. I can't afford super soft ones that need replacing each meet. I would want to get 4-6 trackdays out of them if possible.

Lemming

Cue the graph - the number of heat cycles you get from race rubber is inversely related to your salary and/or disposable income

333pg333

n'yuk n'yuk, there's one in every crowd.
Actually you're 100% correct ...

Tom W

It depends on if you are planning to run radial slicks or Goodyear bias ply slicks. The class I race in requires the Goodyear R430 compound bias ply slick. We get about 3 weekend out of them before they die. Each weekend for us is 6 cycles with 20 minute practice, 30 minute qualify and 30 minute race on each day. I used one set in a 4-hour enduro at the end of last season and did not need a tire change. A set of tires is about $1200.

333pg333

Thanks Tom. We can run anything although I understand that one of those types you mention is rarely used nowdays (the one that requires very little or no camber). The version that I was looking to run are the ones that require quite a bit of camber. I think it sounds like your running the lesser used type so I'm not sure how different they are in terms of heat cycling to the Radial slicks?

analogmike

4-6 laps? It takes a few laps for the Michelin slicks to get REALLY good, unless they are brand new then they start out amazing and slowly go down from there.

With such short sessions your tires will be junk when they have barely any wear on them

333pg333

What would you suggest then?

Tom W

Yes, the bias ply slicks require very little camber (I use -0.5 and 0.0 f/r). While the grip is a bit less than radial slicks, they last a lot longer and are cheaper. They also are up to temp very quickly - within 1/2 lap they are at full grip (and the 1-lap warm-up to do a rolling start has them at 80-90% by the time the green flag drops).

333pg333

Hmm, ok they sound more suitable. In your opinion are they measurably faster than a Hoosier R6 type tire though?

IcemanG17

Try sending a message directly to Mark Anderson....he races his 928 on slicks, typically yokohamas.....he used to have a great source for used slicks...but that has since dried up....

Mahler9th

In my opinion, like DOTS, slicks don't last as long on heavier cars. I wouldn't guess there would be much of a difference between a top-level DOT (like the Hoosier is or use to be) and a set of the finest Goodyear radials. A few years back, the Hoosier DOTS didn't seem to be that far of the performance potential of say a bias ply slick, everything else being equal. Not sure about now.

The bias ply slicks Tom W. refers to only come in 16s and smaller-- so that plus what might be major required set up changes would seem to discourage back-and-forth usage with DOTS. Many heavy 951 cars used on the track (I used to have one... 360 bhp, 3000 pounds) require bigger than stock brakes. I ran big reds on mine, and I don't think there was any 16 inch wheel I could get that would allow room for big reds and 13 inch rotors. Maybe its different now.

I cannot agree with Tom as to how quickly the bias plys get ready. In my experience it is at least a lap, depending on the prevailing conditions. And I don't think they last any longer than radial slicks, but this is just my gut feel.. not based on personal experience.

Tom W

I've never used Hoosiers or radial slicks so I can't compare. My car was converted to it's current form to conform to class rules (it used to be "prepared" and I ran MPSC or RA-1s on cup 2 wheels). My car weighs 2375ish lbs with me in it now, I ran it for 2 years at about 2650 using these slicks too. Less weight is better for wear.

Mike's right 16" diameter wheels are required for the Goodyear slicks (we run 16 x10.5 x 23.5 and 16 x 13 x 25 slicks for our race class). I have "big reds" (in black) on my car and the Jongbloed wheels I use have enough clearance to work.

333pg333

Ah ok, well that excludes those tires then. I have 18" x 10" all round at the moment. I'm going for 280mm rubber square setup as well. This will be very foreign to you rear engined guys but it does work.
Wow Tom, 2375 with you in it!!! That's amazingly light. I can't imagine how responsive that is especially with what I imagine is a high compression n/a motor. Must be a blast to drive.
The reason that my car is so heavy by comparison is that it's still a road/track car. I was getting a proper track car together when the economic world fell apart and my partially built project has come to a grinding halt. So we have a new motor going into my road/track car. It will reach over 500whp so some of the power will make up for the lbs, but then as you illustrate, you have to make this turn and stop. I have essentially the brakes from a 965 mark 2 with the Big Reds and drilled rotors on the front and ones from a 928 S4 on the rear. I actually want to go to 6 pistons and larger rotors but that's yet to happen. Custom KW suspension is also very effective and there are a few mods to bring the weight down. Lexan rear hatch, c/f hood, removal of stock pop up lights & stock electric seats so this should help a little. New Enkei wheels should help with unsprung weight as well.

Anyway, I will try some slicks and go for medium compound to start with. I may 'graduate' to the Hoosier type DOTs if the slicks prove to be too wear prone, but I'm sure I've seen guys stipulate that they get 8-12 heat cycles out of radials but of course that may have been on lighter cars. For us a set of these radials cost over $2500 so finances will definitely play a part.

Thanks Brian, I will see if Mark Anderson can give me some pointers. Mark Kibbort has been very helpful too.