I would measure inside from mounting flange out to bead so when looking at other rims you have a min reference measurement.

also measure wbp to make sure 5 on 4.5" and not 4" or 4.75"

measure from mounting surface to outside of rim bead to get the backspace measurement. I use a yard stick & no tire on rim.

would be nice to mount up the rim to check fit and spin wheel to check each side on runout or bent warped rim.

remember the tire bulge/spring when picking rim & tire combos.

good luck hunting