Sort of an odd question, need to know the tap size for the rotors

[E34 530]

So yeah I need to re-tap the threads on one of my rotors and was wondering what size tap I need to chase the threads.

Thanks, Andy

[E34 530]

gahhhh, meant the hub not the rotor.

[Bill R.]

bolts that hold the wheel on thread into the hub its a 12mm X 1.5