Just to clarify this Hans, are you saying that you sometimes run 305's at the front?? Or 285 f - 305 r ? Do you have to do any body work to fit the 305's? Plus what tyres are you running?

 

I went to the url in your profile, love your car! a couple of neat solutions I might pirate off you. didn't understand everything but I'll have a dutch friend help me out.
I will also be shipping my car to .nl to prep for race season

on your page though, you list 245 and 285?

 

My friend DrRon took the step last year, I am currently rebuilding the to facilitate changes:
New front, new custom build A-arms, wider fenders, wider Q-panels, Kokeln rear axis, 10,5 BBS rims. Oyes, and I also lower the car 2,5 cm further.

You can follow rebuild on this site Will post some pictures of the new front this week.

I could run 305/645 or 305/660 18 Pirelli F/R, or similar Dunlop and Michelin. Will start with 285 though, and see what the tire temp does.

 

Thanks guys great info..............
CUZ

 

I still find it hard to believe that you're intending running 285-305 all round as in same size front and rear but I will follow your progress with interest.

 

The reasoning behind that is rather simple:

1. Weight distribution of our cars is 50/50 F/R
and
2. The tire temperatures on a 245F 285R setup are 80C / 55C
and
3. some serious race cars like the Kokeln Orca (18x12) and Woodies 951R (17
x11) drive a square setup
and
4. with a 245F 285R setup it is hard to get rid of the understeer

All 4 arguments go in the same direction.
But yes, the proof of the pudding is in the eating.

 

Well that all makes sense Hans, thanks. By the way what sort of hp output is your car and how light is it?

Patrick

 

So by the square theory a 355 all the way around would be best?

 

Well by what Hans is saying that would depend on you're hp, but knowing a bit about your projections maybe this is what you're going to need!

 

Not necessarily. Too wide a tire and you won't get up to optimal temperature for maximum grip.
This is a very important aspect.

 

+1 too wide is a waste.

 

Front and rear 355's sounds preposterous to me but if that's the theory re same size all round then this will be the car to do it on...600hp+ eh Guns???

 

Correct, the most important aspect. Without heat in the tires there is no grip. The temperature reached dictates the width.
E.g.in the wet I run 250's. On my car in the current setup 265's would probably be ok. On Woody's now sold 500+HP car he had 12" rims, which would support 335+ tires

My current output is 335 HP, with a 2380 weight. Building a 400HP engine, with a 2315 goal weight.

The car will be 4 inches wider and 1 inch lower, which would gain me in theory 0.25g cornering grip, if the tires stick..

The ultimate goal is to keep up with a 911 GT3 RS. One needs to have dreams,