I have developed a hub / tyre combination for the Zeobot featherweight. It uses a 64mm tyre on a split steel hub. The split hub actually clamps the tyre so it cannot spin on the hub. The tyre is filled with a 16mm diamter neoprene foam cord insert. The whole wheel assembly will fit direct onto a 6mm motor shaft (grub screw), the other side of the hub has an extended 6mm shaft to go straight into an outer bearing so the wheel gets supported on both sides. The Zeobot uses a standard motor with 11:1 gearbox. Makes for a really compact solution. In fact one version of the Zeobot has 8 wheel drive with this set-up.

Paul