I have a 2005 G35 Sedan with full bolt-ons and currently running 245/45/18s, but need new tires. I was curious as to sizes people have had best traction with at the strip? I was thinking about going to 245/40/18 since my current sidewall looks a little big for my OEM 18's, but am open to suggestions.

 

Shorter tire won't do much for you really but create more wheel gap. The 245/45-18 is most popular size used.