The complete metric wrench set

[KEH]

21 mm fits lug nuts that 13/16 also fits.

KEH

 

[Deadhead]

I work on Massey Ferguson tractors and combines, Fendt tractors, Deutz and Perkins power units, and many different types of equipment for different manufactures. I have metric up to 50mm and standard up to 2". If we need bigger it is provided by the shop.

 

[redwrench60]

If you mess with enough machines, cars and other junk you'll eventually use all of them. What's more basic than wrenches?

Plus they make people scream "holy ****!!" when you open your wrench drawer.

 

[devan7815]

If we're talking combo wrenches and not sockets, 8-19,21,22,24,27mm. A 20,30,&32mm would be handy to have around for occasional use. There's also the configuration issue as well. There's combos, double box-end; double open-end, offset, stubby, and ratcheting versions as well.
As far as sockets go others have already made good suggestions. The fact of the matter is that if you start wrenching a lot, there's just no telling what you'll wind up needing.