I bought a set of these a while back and think it's the one of the best purchases I've ever made.
http://www.machinemart.co.uk/shop/produ ... t-grip-set
I've even used the smaller ones for gripping rounded bleed nipples & studs.
If you're careful, it's possible to remove locking wheel nuts too, with only cosmetic damage.
They do 2 different sets, so if you're going down that route, let me know & I'll see which size is the best bet.
P.S. In the meantime, don't forget to pop a bit of penetrating oil between the nut & wheel. Try to reduce any friction anywhere as they will be extremely tight if you've not had them off for a while.............as you've probably noticed.
Good Luck!
A