I know about the wheel calculator and all, but what is the acceptable difference between front and rear sizes? How much (2%, 1%, 2.5%?) before the ABS computer thinks a wheel is locked? I'm thinking of going 265/40/18 on the rear and 245/45/18 on the front. Will the 1.3% difference matter? The wheels are 8" wide so I am a little hesitant to go to a 235/45 tire. TIA