EE WAS ATTEMPTING TO REMOVE AN 0-RING FROM A 785HAUL TRUCK TIRE & WHEEL ASSEMBLY. THE WHEEL ASSEMBLY WAS STILL SEATED TO THE TIRE BEAD ON THE BOTTOM SIDE OF THE TIRE. WHEN THE WEEL BROKE LOOSE FROM THE BEAD IT FELL CATCHING EE'S FINGERS BETWEEN WHEEL & BEAD RING ON TOP SIDE OF WHEEL CAUSING TIPS OF FINGERS TO BE AMPUTATED.