Here’s the scoop:
We will be making 3 versions of this wheel, eventually.
6" diameter wheel is in production now. It is being molded out of black polycarbonate, just like the inside of the FIRST Kit Wheel and the Plastic Omni Wheel. The wheel will come with 12 fasteners (#10-32 screws and nuts), but without tread. We will have tread available, but not included. The target price of the 6" wheel is around $24. We hope to have the 6" wheel available within 4-5 weeks.
Depending on the demand for the 6" wheel, we will make a 4" wheel this fall. This won’t be available until much later this fall. Price will be a bit lower than the 6".
If demand is really high, then we may make a 8" version soon. I don’t know if we can afford a third mold. This version may be for next summer.
As for the design, this is inspired by the 60/254/968 development of this sort of tread attachment technique. Hopefully, these treads will not need a rivet at each end of the tread, but we shall see once testing begins.
The 4" and 6" sized wheels are designed so that PVC pipe can be sandwiched between the two halves in order to make the wheel wider. This is our design theory, and has not been tested yet. The 4" wheel is designed to accept 3" PVC (od = 3.5") and the 6" wheel is designed to accept 5" PVC (od = 5.56) in order to create wider wheels. I suppose that someone could make a 12" wide wheel (or whatever size), if all works out as planned.
The hubs for these 3 wheels are all the same. They accept a 1.125" od bearing, and they also can accept any of the live axle hubs that we sell (500 key hub, 375 key hub, DD Globe Hub, 500 Hex Hub). Of course, they have a 1.875" bolt circle.
I will update our website so that people can see CAD pics and download CAD models. Hopefully, I will do this soon.