Originally Posted by InspGadgt

That largely depends on the mounting method used on the tires and the plastic used. The older sets used a contact cement type of glue on the foam so you could just soak the rims in lacquer thinner and the foam would come right off. Most of today's sets use CA glue and the rims don't take well to being soaked in a solvent. On those types of rims the best thing to do is use the tire truer and true down as close to the rim as you can get.