You couldn't make up some of the crazy stuff happening in the world today, and nobody would believe it was remotely realistic if it was presented as fiction.
Past a certain point, the plastic becomes permanently softened, and there's really nothing you can do but fabricate new rims or replace them.
For everything previously posted here on the subject, search google:
tire melt site:www.modelcarsmag.com
You gotta do what you gotta do to keep things running smoothly.
I'm sure everyone will appreciate the work you'll be putting in and forego whining about their inconvenience.
Yup. Or even plain old 1-part lacquer clear.
That's the safest way to handle metallics or pearls that blush, too.
No chance of getting blotches from overly aggressive sanding or polishing disturbing / unevenly uncovering the metallic particles.