I like the "look" of 15's too, and firmly believe that the ratio of sidewall to wheel OD is a critical value - I'm running 15's with 70series. That said, the market has migrated away from 15's, they can make it tough to fit disc brake rotors and it's almost impossible to find speed rated tires in 15's (pointed out by Jerry). I love the look of my highboy "pro-cruiser", but I can see a pair of 16x10 or 17x10 Cragar's in my future as tires become harder and harder to source. You'll never see 20's or 22's on it unless it's owned by someone else!