Coming to this party late but here is some more info. When I was going to trade school with my buddy, the local repair shops used the students as cheap grunt labor. Because we where learning mechanical repair they could use us to fix things we had learned in school. I went to a A/C shop, but my buddy went to a tire repair shop. The first day of work, he noticed a large hole in the roof above the tire cage, and red stains on the wall. When he asked one of the other tire guys what was with the roof, he was told "that's the reason your here to replace the previous guy who didn't use the tire cage". Turns out the last guy was in a hurry and decided not to lock up the tires in the cage. When he went to inflate the tire, the ring blew off at about 80PSI. Took his head and part of his shoulder right off. The roof got repaired a week later, but my buddy never forgot the lesson !The local County employees here have an eye-bolt sunk in the concrete in their tire shop, they put a chain through the center of the rim and around the tire to catch the lock-ring if it pops off while changing our deuce tires....
A local tire shop has a "cage" they put the tire in while changing tires on deuce type lock-ring rims.
So is their really a danger of the ring poping off and getting you????
One of the tricks used in remounting he taught me was to use "Talcum" powder on the inside of the tire to allow the tube to slide around without binding. This would prevent the tube splitting. Also airing up the new tube (just till it takes it's full shape) in the tire, then again using talcum powder (baby powder). He would install the flap (tire boot). Then more talcum powder on the flap, then the wheel will slide in much easier.