The split rims require a special-shaped pry bar to fit a small slot where they join in the center. It's almost impossible to get them to separate without it. No, there's no danger once the air pressure is gone, but the beads still have to be broken down with a tire hammer on both sides before the pieces will separate. If you don't have the right tool, just let the air out and get a professional shop to dismount the tires.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!