Re: Smaller Diameter Wheels - What's the advantage?
 

A couple years ago, 968 did a test with 4" wheels, and roughtop tread of two widths, I believe about 0.875" and 1.625". The wider wheels were able to push with approximately 30-40% more force than the 1" wide wheels. However, we determined this was not in our strategy of game play, and not worth the added weight/space.

Anyhow, we have increased our tread width slightly over the years, from 0.75 back in 2005 and 2006, to 1" in the present season. Primarily, this was done for wear reasons, but also for a slight gain in traction. I suspect there is a limit to the benefit of "digging in" to the carpet, and some benefit to be gained by interacting with a greater quantity of fibers.

As mentioned above, in physics class they teach you surface area plays no role in friction, which is correct, for [perfectly rigid surfaces (tire included). The same cannot be said for real world scenarios. This is why you don't see dragsters running down the strip on a pair of skinny Honda Civic spare tires.