You'll find that on most modern cars the wheelnuts are a 60degree conical taper type regardless of steel or alloy wheels (motor manufacturers tend to standardise to keep their costs down). I use same nuts for winter steel and summer alloy wheels on my wifes Jazz. There are other types like a semi-circular dished type, a good tip is to put a thin smear of copper grease onto the taper hole in the rim and push nut into the hole and twist it, pull it back out and if the grease has wiped off onto the nut taper and is a nice even covering all over that's a good sign as the shapes match, be sure to wipe the grease off the nut and out of the taper before finally fixing the wheel on though, the taper should be dry when assembled, although a thin smear on the thread won't hurt (especially on an 'open' nut, but with a fully enclosed 'acorn' nut the water won't get in and rust the thread anyway so not so much need of grease)..