bigger wheel = wheel closer to the ground, which means less rubber between the wheel and road.. less rubber = less bending on sharp turns, better handling? smaller wheel = more rubber, the sides of the tires bend with the turns and not as precise handling? never cared too much to find out how much of a diff it made but i doubt its really noticeable....shouldnt really matter unless ur racing on the track? ^^ also usually bigger wheel = more weight.....