This is a post earlier this year by CDR. Just wondering others thoughts on this, as I missed this discussion earlier.
"I kept the original size on the rear (245/45-18) and went for a wider tyre on the front:
245/40-18
The result is that the car is much less prone to understeer in the dry, and the feeling is much more neutral between front and rear. I based my decision to go for the same width front and rear on the fact that this is what many japanese tuners are doing with the Z (Amuse, Mines, Boss, Sunline Auto etc.).
Before anybody says different - 245/40-18 from BF Goodrich (which is in fact Michelin) is the same diameter as the original 225/45-18's on an 8" wide rim. This means the stagger between front and rear is unchanged, and their are no problems with ESP.
I've tried this setup out on a few tracks and it's very good My friend has also tried the Falkens on track, and complains all the time about the soft sidewalls."