14 inch big bolt steelies and disc brakes

Now I'm slightly confused. I thought that the rotors were set up for big bolt pattern lugs.

On the rotor the measurement from behind the lug to the center of the next one across is 4 1/2 and the diameter of the center hub is 2 3/4. I thought the big bolts started at 5.5 for the same measurement The rim that I removed, which I thought was a small bolt pattern rim measures 4 inches from lug hole to lug hole and the center bore is about 2 1/2. I hope don't sound to crazy, but I guess I need a clarification the measurements. Thanks!!20210311_072357.jpg20210311_072417.jpg20210311_072445.jpg20210311_072504.jpg