I was on the way to the ferry early one January morning with a load of gear in a vw pickup. A 'nice' load to make the journey worthwhile. Just as I neared the ferry terminal I heard a strange vibration from the rear wheel then bang. managed to pull up and the wheel drum was sitting on the inside edge of the rim. All 5 studs had sheared at half 6 in the morning, Belfast port. Nightmare. Rang insurance, road side assistance. Noone available til 8. Had a good while to think about it all. Where would I get studs, probably need a hub as wheel cos the sheared threads are never coming out...a fortune. Eventually the recovery lad rang and organised to go get studs from a motor factors and said he'd be down in 45 mins. Duly arrived with a jack, cordless drill, easy outs and a vice grips....not even a tapping handle mind. I said here we go...the little shop of horrors..
He proceeded to drill thru each stud and they wound out effortlessly. When they have sheared like that the stress is gone, the slightest turn and they work out.
My advice, try and shear the bastard and do the same..... Would never have believed it.