Pretty interesting article, not sure if anyone saw this or not...

Effects of Upsized Wheels and Tires Tested - Tech Dept. - Auto Reviews - Car and Driver

 

are u trying 2 say your 18" wheels make your car better than those w/19"+?

 

there was a thread about this EXACT same thing posted really recently (same article and everything)...basically there are subtle differences in wheel sizes (duh) but when it really comes down to it unless your G is a pure track car it probably won't matter at all

 

Better in a straight line yes

In the tests however, they reduced the width of the tires which played a role in hurting the skid pad performance as well