I looked more closely at my aero inserts; the center black cap is glued onto the insert, so I can see how this whole assembly would just pop off and on. When I picked up my car I had them install the black lugnuts and silver center caps (see pic). I didn't see the silver caps before they were installed, but it appears the silver caps actually pop into the center wheel hub on the car. In order to snap on the black aero inserts, I need to have the silver caps removed. I'm thinking this might require removing the wheel and pushing the cap from the reverse side (just a guess). I really like the look with silver center cap, but if I'm right about getting the silver caps off to install the aero inserts, it certainly complicates the issue.
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