They were used all the way up to just a few years ago when they started phasing out lead. I'd hazard a guess that yours was typical of the 1960's through the 1990's.....maybe a bit earlier or later......they didn't change much through the years. Yours was designed for steel rims, not the alloy ones. They were hammered onto the lip of the rim. The alloy rims used glue-on type weights.