[Holtzman]

Contrary to popular belief, size does matter.

Both large and small wheels have there benifit. Large wheels are able to roll well over bumps, stairs, ledges and so on. On the other side, as a robots wheels increase in size, its wheel base decreases in size making it very unstable. We saw countless examples of robots this past season that had the 12' skyways. (props to team 69's unique expanding chassis design to counter act this problem)
Small wheels do not roll well over obstacles, but in a year like 2002 for example, where there were no field features, there is no need for large wheels, and you can use something smaller. Smaller wheels are also lighter, and anyone who saw 1114's robot can attest to our weight problem.

We at 1114 used a 3 3/4 inch wheel in our strafing design to minimize space while also minimizing the amount of reduction needed in the gear box.

So, in my opinion, unless theres some field features that require a large wheel, go small, there's no detectable difference in traction between a large wheel and a small wheel and there are real advantages to small wheels.