As you can see the wheel studs have sheared off allowing the wheel to bounce off down the road. It was a combination of things that contributed to it. A VERY small bearing surface where wheel meets hub. A few hundred kilometres of REALLY bad roads. And possibly a bit of over tightening of the wheel nuts. Apparently it’s also more likely to happen with alloy wheels to. So keep everything clean, do not over tighten your wheel nuts and take it easy on really bad roads.