IDK how wheel size might affect milage, seems it depends on how you drive--if you drive like a nun, you might not notice any diff. And alot of guys are running big & or heavy wheels, but from what I read, the stock trannnies in our cars arent designed for it & generally cant handle it. Case in point, GT500 replicas. I think they are hot, & seems to have reasonable, competitive prices, & I see them on GPs (looking good), but how much do they weigh? I could not find any tech info, but users reported 18" ~25+lbs & 19" ~28+lbs. Stock Enkei torque 5 star are ~17lbs, which is light even for 16", which is also designers' intent. IMO, pretty big increase. Its my understanding its not the dead weight, its the weight acting across a distance in the rotation of the wheel that wears on tranny. Again, I see guys w/ 20"+ that I know weigh 35lbs+.
So depends on you, how you drive, condition of you car, how much youre willing to put into it, how deep you pockets are, etc.
I say, do homework, get what you want, deal w/ the fall out when it comes.
