An amusing anecdote: My spouse's new bike came with tubeless-ready rims, and it is extremely difficult to get tires on and off, even with the bead jack that I've used successfully on other bikes. There's no way that her hands will ever be strong enough to deal with a flat while on a ride, even if she brings the bead jack along, and she's quite mechanically inclined.
Another pair of tires that we tried was so tight that we couldn't mount the rear one at all. We were very careful to keep them in new condition, did not ride on them, and the shop graciously took them back.
I started a thread on HN at the time, and received some replies to the effect that this is a common problem with tubeless-ready rims. Now I know what to avoid. A more recent thread, that I have no hope of finding, suggested that manufacturers have backed off on the designs of those rims.
Measuring the absolute diameter of a rim would be difficult with home shop tools, but the difference between two diameters should be easy with a yardstick and a few odds and ends.