This is ancient history, but I drove school buses in Estes Park back in the early mid 80s equipped with drop down chains. Probably logged several thousand miles on them.
They worked well if you followed a few rules. They did have a speed restriction. Can't remember what it was, but if you drove too fast with them engaged they would break the chains off. When coming to a stop I would activate them at about 10-15 mph so that when I came to a stop they would be under the tires. Same thing when starting. I would turn them off after speed reached 10-15 mph. If the ice/snow was patchy with dry pavement showing it is problematic. They drop down chains to require maintenance as the chains would sometimes break off.
