I believe I understand what hes asking but I don't have a wheel to measure.
Best way I can describe it would be to look at the photo below and say that he is looking for the ID of this rim. But not this one, the vmax one. So, if he were to cut the rim section off the vmax wheel, would it fit inside of the rim below and be able to bolt up or is the vmax "disc" too small to reach the mounting points?
I would guess the vmax "disc" is too small. That is why I wondered about using a blank like the one Przemek posted. Either way, its all above my capability and knowledge. Good luck!