I think that getting a tire off a rim without a couple of old fashioned tire irons (how many of you have ever seen one, let alone used one???) and a maul would be sooo hard it would not be worth the effort. And cutting one off would be difficult, dangerous, and really dull your knife. I would suggest just letting the air out (air expands with heat you know), then light the sucker off. Assuming that you get rescued, new wheels are cheap...