When melting tire weights. Use a fan to blow any fumes in a safe direction. A few years back I was melting tire weights for Salmon balls and I nearly hospitalized 3 people. I don't know what was on them but it made 2 of us (myself included) blow chunks. Washing the weights 1st might help, but it might have been from the weights with the adhesive backing. Anyways, use plenty of ventilation.
Tight lines,
Wade