They are dangerous! I used to work at a small service station.We would put them under the arm's of the hoist and stand way back while inflating.Sometimes they were really rusted on so the boss would pull the ring put em under the hoist and pour an entire bottle of coca cola on em,put the air chuck on and go to the other room,inflate just a bit and wait.took about an hour on some but you'd hear em pop.I know not recomended procedure but it worked for him.personaly I don't like em anymore!