Jim H.

Alright Cos and GT3 Nut, You guys win. I was allowing for a "singularity" but with at least two people having the same problem, it is probably best to wait for the new sizes. No sense in trying to add to the stories of ABS failures.

Thanks much.

NJ-GT

The 335 I have is smaller in diameter than the 305 by almost 0.46" (25.94" vs 26.4"), and the 275 front is taller than the stock tire (25.5" vs 25.2").The Michelin Slick on the Cup car is even taller (26.77").

The problem seems to be on the diameter differences between front and rear. So the safe bet is to stay close to the factory setting: (25.4" F 25" R ).

I ran the following combos on track days at WG,LRP, Poc without ABS issues:

V700 ECSTA 265/35 305/30
MPSC 235/40 295/30
MPSC 265/35 315/30
MPSC 265/35 295/30 (my favotire setup so far)
SSR 265/35 285/30

I have tested the following setups on street an autocross without ABS issues:

A3S04 245/35 305/30
A3S04 275/35 205/30 (my favotire setup so far)
SSR 265/35 285/30
V700 ECSTA 265/35 305/30
MPSC 235/40 295/30
MPSC 265/35 315/30
MPSC 265/35 295/30
SSR 265/35 285/30
RA-1 275/35 335/30

On my next track day I will run both the RA-1 and the 265/295MPSC. I'm going to get lap times from both, and report on that.

SRL

This link answers all your questions re: tire size and wheel size.

http://www.world-challenge.com/compe...ppendixa-4.pdf

And just for fun, here are the Vehicle Technical Specifications for all eligible Porsches in SPEED GT:

http://www.world-challenge.com/compe...t3-_98-04_.pdf

http://www.world-challenge.com/compe...1-gt3-_05_.pdf

http://www.world-challenge.com/compe...urbo-draft.pdf