Originally Posted by Aero
I also wonder what condition any plastic part would be in when its in such close contact with a 300+ degree rotor...
The same argument would apply to the protective caps over the slider pins in your brake caliper. They seem to survive.
Thermoplastics have higher melting points and can withstand greater temperatures. For example PTFE has a melting point of ~330 *C and PEEK is ~345 *C
The kosei rims that I just picked up came with a set of plastic rings and were used on a track-only Civic.