Wheel bolt spec?

Brilliant. I'm converting to studs and just in case the kit from the Cup racer I've ordered isn't quite right, I need to know what I'm looking for.
 
I can't understand why any car maker uses bolts instead of studs, studs make changing wheels a million times easier
 
Cost I guess? The studs were surprisingly cheap @£.170+the vodka each from Renault, but the nuts were insane. So, gone for group N coppered ones which are still £4.00 a pop.