I don't weigh much. It's the centre studs that have gone - erm, I don't think I could possibly spin the rear wheel on bare pavement, I'm an ordinary mortal, not Thor or The Hulk.
Schwalbe UK are sending me replacements. They say it's probably due to the crap state of the roads I'm riding on. They are probably right - I regularly hit debris such as lumps of wood, stones the size of plums and rough broken surfaces.