Originally Posted by
HillRider
Do the measurements FBinNY suggested at several places around the circumference and average the results. Most rims aren't precisely circular.
Yes, I should have said that. But IME small rims of toways heavy extrusions tend to be very stiff and round. It's not like 300gr 700c rims that might be oval varying by 10mm depending on where measured.
So play it safe, measure 2 places at right angles, and if they're the same you're good. Otherwise measure one more direction and average the three.