[BigE]

Just remove the wheel and push the cap out from behind. Their instructions are so you ca replace them without removing the wheels.

 

[BigE]

I already orderd mine so as soon as they come in ill post pics and let you know the quality... they look plastic to me actually. The only thing I think you would have to worry about is using too harsh a wheel cleaner and damage the coating on them.

I believe all the factory wheel centers are plastic.

You might want to try giving then a spray of clear coat before installing them, maybe even stop by you're local body shop and ask if they can give them a spray next time they are clear coating a car?

I have a roll of 3M clear vinyl, the same kind used for bumper/rock guard. I wonder if something like that could be used to protect the caps?