Cragar wheel question

I would like to order Cragar wheels for my car but am concerned with the disc brake calipers possibly hitting the inside of the wheel. I have the Cadillac conversion rear disc brakes on my car. I want to get 15”x8” wheels but don’t know what the inside diameter of the wheel is. Summit racing doesn’t have that measurement and I didn’t get a call back from Cragar regarding this. Does anybody happen to have one off their car that could give me this measurement? Thank you in advance for any help with this.