Mine are already installed so I can't measure them however one write-up says the rotors are 11.65".
If they can make custom rotors that would be great. I borrowed a friend's drill press and used the old hub ring as a template then bolted it down to the rotor.
I forgot to mention we placed the old ring on the rotor and measured from the end of the ring to the end of the rotor hat. We took four measurements and made sure they were all the same. Be careful when drilling the hole that goes through the original hole, the bit tended to want to walk when we were drilling it out.