Back in the '70s when most OTR trucks where spring ride truck owners that where leased to the company I was kept spare springs at some of the terminals where we had to lay over. (Wichita, there was a hole in parking lot, drop wheels in that hole could change without a jack) Now when we where waiting for a load, the tractors where driven all over town just like a car. Most of the springs that broke we where bobtailing. I would often run over the rating on axles. That would cause springs to loose there arch, and wear hangers and other things, but never broke the spring. Of course, when they lost their arch I would replace, because I don't want to look fat, so that might be a issue with RVs