There was the Weinmann 514 (A124) and the 516 (A129) which were 20 and 22 mm in width respectively, Yes, they did not have a bead hook so you should only use a wire bead tire on them, and not too much pressure. 100 psi max I would guess, depending on the tire. They made an OEM model with no eyelets, but mostly you see them with single eyelets. They have hollow channels in the corners for strength, and were generally a very strong rim, and built up nicely, although the concave section makes some spoke wrenches contact the rim surface. I have one 36 hole used one in rebuildable condition if you want another. $20 shipped.
Bob Freeman