Because they use slicks to improve traction and use the small diameter, lighter wheels to offer the fastest acceleration possible ! There is also the point that the slicks have fairly high profiles so, although the wheel is smaller, the actual tyre has a fairly high rolling circumference. So, the smaller the wheel, the smaller the tyre. There are obviously other reasons to use the higher profile slick tire but, that's a not what was asked !kenan said:If this is true then why to the big poer GTRs all run on small wheels for drag racing if they will loose traction for example the sumo 34 and the top secret 33
Just to add to stumo's point, if the smaller wheels are heavier than the larger wheels, this will also be an exception to the rule as, the heavier wheel will take more effort to turn and overcome its higher inertia !