As I understood it, there is actually another wheel/drum under the seat area that is in contact with the rear tire and spins it negating the need for a chain/belt/shaft drive. I believe he said there are about 160 bolts holding on the rear tire to the rim (bead lock style) but it can be removed in minutes by only a couple bolts.
Also, the tire, the biggest bike tire in the world, couldn't even be put on by onther shops $42,000 tire machine. He had to devise a way himself to put it on and now there is no ptoblem. Bike tires, by nature, have very stiff sidewalls, so much so if you ride conservatively you CAN ride a flat without damage to the tire or wheel if you dont lean it much until you can get a fix. How a tire that wide and low profile, as a percentage of width would handle a flat, i cant say.
S.O.