I searched for this. but couldn't find anything...I want to keep my stock rims (I know, but I really like them) and add all-seasons to my Z (allthough finally got a letter in the mail about the Potenza and suspension recall, 'bout figgin' time..so I get two new RE040's, whoopie)...anyway, based on tirerack, I see that the ContiExtremeContacts have the best all around rating...anyone have these on..I figured I'd go with a 255/40-18 on the back and 235/40-18 on the front (2.4% difference which is about as close as I could get to the stock 3% diff.)...all so, whould I really notice the difference (besides for sidewall height and a little rougher ride)