Brakes are directly related to wheels size! Decide what size wheel you want. Most will recommend you go for a larger diameter rim because good quality ADR approved (Z rated is that right?) rubber is easier to get then say 15 inch rubber! You'll have little trouble fitting decent brakes (ie big rotors) within a 17-18 inch rim.
What I mean is don't expect to get a 330ml rotor in a 15 inch rim!
