jrgordonsenior

No that's crazy thinking. The only way to know what works best on your car is to take pyrometer readings across the tread on both the R6's then the new slicks. That will tell you how you're using the tires.

Many of the IMSA cup racers are running less than 3.5 f and less than 3.0 r these days on their proprietary Yoko slicks. I'm running -3.2f and -2.7 rear on my 2600lb. w/driver 996 on either R6's, Yokes, or Hoosier slicks. They all test about the same across the tread, the slicks are 2-3 seconds per lap quicker. 700/900 springs.....

333pg333

I would just put them on and go from there. See what changes had to be made.

So when you say they're 2-3 secs quicker, do you mean over R6s? What length or time track?

SundayDriver

Victor - I think those generalizations are just that and not necessarily true. I have seen plenty of cases where recommended camber for a given slick is equal to or less than R DOTs. You have to look at each tire. If the slick in question happens to be a bias tire, then you need far less camber - generally 1/2 to 1 degree neg camber for bias slicks.

As far as the springs to get more heat - I understand and agree that would create more heat, but that is not the best way to go. Why would anyone want to give up grip & slide the tire to generate heat, except as a last resort? Put the right tire on the car (size / compound) with the 'right' alignment specs for the tire, and you will get the needed heat. If you need a bit more heat, I would be more inclined in increase toe (in or out) to get that additional scrub and add heat.

In regards to 'what is a slick' - they are NOT usually bias tires, at least in the context of this forum. Most of the slick used on P-Cars are radials. Most of the sports racers / formula cars in SCCA use bias slicks. Slicks have NO tread and are NOT DOT certified. The Hoosiers that are mostly discussed here are DOT tires, not slicks, but many call them slicks. Real slicks generally have less rubber depth, no thread at all and generally softer compounds than DOT R's.

Summary - IMO, there is no 'automatic' setup change appropriate to move from DOT R's to slicks.

joseph mitro

"confusion" is a good way of saying it.
Again, "slicks" generally means a non-DOT approved race tire that is not approved for use on public roads.
There are bias ply slicks (as noted below by va122) and there are radial slicks.
Bias ply slicks, from my understanding, need LESS camber due to their deflection, whereas radial slicks need MORE camber.

agreed. I'll also add there's a huge difference in types of slicks. my Hankook F200 slicks were quite a bit slower than the Hoosier R100 slicks that I bought as GT3cup takeoffs. there are different compounds and different grip levels. Yokohama had (or still has?) 4 different compounds.

"slicks" are sized differently than DOT tires......DOT tires will have the traditional sizes with tread width/aspect ratio/wheel diameter;
non-DOT race tires are sized as tread width/overall tire diameter/ wheel diameter

not true. agree with jrgordonsenior

joseph mitro

agreed. in fact, some of the top BMW club racers (B.Watts is an example) use both R6s and true slicks. I don't know how much of a setup change he does, but the best setup would involve data testing.

for me, being the crew chief, driver, tow rig operator, etc........it's difficult to optimize the setup by making changes between sessions or taking tire temps or whatever.

SundayDriver

One of the big advantages of a purpose built racecar is the ease of making changes. I could change front camber on the Stohr in ~5 minutes. Rear was a much bigger deal and could take up to an hour.

HJK

Hey Guys, thanks for the replies, just back from a weekend "culture" at Angkhor Wat" in Cambodia.
I'm with you all on the camber, but adjusting camber for me is not categorized as "changing your complete set up"

If the expression refers to camber adjustments and maybe more spring or sway due to body roll, I'm at ease, that I can figure out.

I was just taken aback by people I talk to and say aaah, you want to race slicks, you must change you the whole setup....

I'm cool now. Will let you know how it goes on the Michelin slicks....

Thanks

HJK

I haven't weighted her empty yet, this was my end of race weight two weeks ago.

Henk

va122

You are absolutely right they are generalizations. I was just gong off what Hoosier told me when I started using their slicks. This thread is really educational.

jrgordonsenior

Yes over R6's which I ran for several months when I first built the car 1 year ago. I also lightened the car by 100 lbs. and that definitely adds to the difference but power, gearing, suspension are all unchanged since the original build last summer. Laguna Seca 1:35:0 vs 1:38:0, Cal Speedway 1:45:6 vs 1:49.1, Buttonwillow 1:59:0 vs 2:02:4....

joseph mitro

I think if you want to get absolutely the very last degree of performance from the car, then you would need to completely reevaluate your setup....spring rates, shock settings, alignment, sway bars, tire pressures, etc. and change these based on testing.

for me as an amateur that's simply not feasible from a time or cost perspective. my setup is good enough at my stage of learning, now it's just focusing on being consistent as a driver and getting the car's max performance as it is now