I suggested to some folks on another site that they check bus (school/commercial) and heavy truck garages to obtain the big wheel weights (1 to 3 1/2 pounders) that were used on the big dual wheel assemblies. These weights will crack or break (don't know why) and are usually discarded. I started back in the 1970's by getting weights from Greyhound and Trailways and the Utah State Roads Dept. and school district bus garages.
A fellow responded that he didn't think they used lead weights on the dual heavy truck/buses anymore. Anyone know if that is true?