I think recaps were more common before the use of radials (1940's-'50's). I know my dad (used car dealer in that period) often fitted them and we took a Florida vacation in a 1959 Lincoln in 1962 with recaps installed. On his return from service in Europe during WWII he worked with a friend and a New Jersey recapper on making a snow tire tread to be stretched over your regular tire. I remember seeing a magazine article in the '60's about a Pirelli carcass being designed which would have a replaceable tread installed according to the season. I guess neither my dad nor Pirelli went anywhere with the idea.
I've bought used tires many times--but you do have to inspect them carefully for even wear, dry rot, bubbles, etc---and to see them rotate without wobble before they go on the car. -- Dave