dude, thats exactly what i needed - cheers
the resins used in some PC/ABS blends seems to have a melt point of 260 degrees - suggests that coating them should not melt them at a lower cure temp of 180 degrees.
forgot to get the centre cap from the 33 gtst rims i have, if the makeup of those is the same then a test on those will let me know if they will survive.
if a photo can be taken of the back of it to display the re-inforcement setup of the caps, this will give a good impression of the likelyhood of shape change at these temps.