Woah, that stuff is interesting. I wanna do something like that!
Yeah, this has me eyeing all the donut spare tires in late model cars and trucks. They are skinnier than the rubber on atomiczombie's creation, come in wheel diameters of around 12" to 18", are very cheap and are usually unused or so lightly used they are like new. A bike using two equal-sized ones would look sorta like Judge Dredd's Lawmaster...
Thanks to bentbaggerlen and atomiczombie for a cool idea!