Above: LOL!
wtf where that tire come from !? 
Woah! Dude's really lucky to still be breathing! Sudden head shot with enough momentum left and had the impact jerked the neck wrong, snap, it's over...
As for how it happened, you had some kind of high speed car collision I suppose, the slam of one car into another broke a spinning wheel right off and it kept on going... The bolts on the rotor must've been in bad/rusted condition too I guess, I dunno, for a complete break off and to still have spinning momentum, I would've liked to have seen the physics of how that could happen!
That is some f*cked up shit though! Next thing you know the store owner gets sued for leaving the door open, heh!
