Changed to Winter Wheels but locking socket rounded off. A bit soft metal it appears. I have had to order a replacement set. I hope wheels will stay on with three bolts.

Torqued up properly you should have no problem. This is the standard method of dealing with losing a set of bolts down a drain when changing a wheel, one bolt from the other 3 wheels..

Replacement arrived promptly. I fitted them today. No wheels were injured during this procedure. One knuckle was grazed operating the jack.

Wheels were stuck to the hubs really tight. They felt like they would have stayed in place without any bolts. Will take them off on a warm dry day and paint the hubs and drums, maybe!