would a smarter mind than mine please explain this to me?? how does the tire stay in place if not for a bead-rim-lip to catch the tire bead and hook it? how does the tire stay in place if theres no lip? the pic looks like a standard rim bead/lip but with a wider wheel rim at the bottom. what am i missing?
OK I will try.
Have you ever looked at a car wheel? There is a "drop center" which makes mounting the tire possible, and it has no "hook".
Lets say you have a tire than measured 20 inches diameter from the inner most portion of the beads. The wheel that this tire mounts on will have a drop center of perhaps 18 inches to allow mounting. The the bench that the bead sits on will have a diameter that matches the tire (20 inches). The rim of the wheel will be greater than 20 inches (perhaps 21 inches) this prevents the tire from coming off.
Because the wheel rim is greater diameter than the tire bead, and because the bead is the same diameter as the bench, the tire can not come off unless the bead breaks, or stretches. It can only be dismounted by pushing the tire bead off the bench (inboard) into the drop center.
Here is a link with pictures. http://www.procarcare.com/icarumba/reso ... wheels.asp
Here is the photo to consider. Notice how there are no hooks. Once the beads are forced outwards onto the bench, it can not come off the wheel.