CHANGING A TIRE ON CAT LOADER, WORKER WAS DISMOUNTING TIRE WITH A RAM 1800 BEAD BREAKER POSITIONED ON BACK SIDE OF RIMBASE. TOOL WAS PROPERLY SECURED, BUT POPPED OUT STRIKING EMPLOYEE IN THE FACE, KNOCKING HIM TO THE GROUND. HAVE REASON TOBELIEVE THAT RIM SECTION FAILED CAUSING THE BEADBREAKER TO SLIP. HE WAS TREATED AT HOSPITAL FOR STITCHES, BRUISES AND BROKEN NOSE.