[ngreen]

We use go-kart racing slicks. They we like 9" last year and 12" this year. We got them from Carl's Tires (local) but I imagine you could find them if you look. They are pneumatic, rubber, are wide and have a lot of traction. They work great on carpet, and the plastic surfaces. I've yet to see anyone push us with those wheels on the ground. They are connected to sproket with machined hubs. But downside is in the weight. This year each wheel weighed in at about 6 pounds. That is about 24 pounds of wheels.

BTW, I like the wooden wheels. I've made eduwheels out of foam board and electric tape.