I am an old man so I can remember way back. The only steel rims I can remember were in the 1930s on what I would call hack bikes; the bikes that teen age boys and old women ride. Prior to the balloon tires around 1935 these bikes had tubeless tubular on steel rims with a wood core. The balloon tired bikes had all steel rims. After WWII I don’t remember anything but aluminum clincher rims on popular bike that would be ridden by college students. Racers generally rode on either aluminum or wooden Italian rims with sew up clinchers. The American tire company, US Royal (Rubber?) made a tubeless tubular that was used by racers for training and some sport riders. We called these tires US Mules. Punctures were easily repaired with a little rubber band injector. These rubber band repairs often failed at the worst times, however they got easier to repair as time went on and the hole got larger. It is of interest to me that a company in the Czech Republic has come up with the TUFO line of tubeless tubular tires. One model has a beaded rubber rim mounting system that enables them to be mounted on clincher rims. They also offer this same tire for mounting on a conventional tubular rim. A “tubular rim” is a rim that is designed to mount tubular tires. It may be hollow but that is not what I am referring to. See:
http://www.tufo.com