One of my 20" folders has a rear v-brake that rubs when the rear rim goes out of true (i weigh 200 lbs. +). Would i be better off with a rear mag rim? What kind of weight penalty is there, and will a mag rim hold a tire at 65 psi +?
The rim shouldn't go out of true under your weight.
Small wheels are normally stronger than the more common 27"/700c versions.
I would suspect the wheel needs truing and the spokes tensioning properly.
Ride hard or ride home alone!
The problem is systemic--truing is always needed with v-brakes on spoke wheels from time to time. So i was hoping to eliminate the need by switching to mag wheels. But, not having one handy ( i live in thailand, where mag wheels are rarer than virgins or working vending machines...) i can't just compare their weight to an alu, spoked rim. Over 15 kg's total i can't realistically fly with the bike. Mags would also lessen the probability of damage by the usual terrorist/baggage handlers these airlines hire.