Center Cap Painting

You should be fine if you follow proper painting protocol. There are MANY ways to do it. I'm an experienced painter, and here is how I'd do it:
THOROUGHLY clean the wheels. Then wet sand them with 320 followed by 400. Sand out all chips and nicks. Then THOROUGHLY clean them again with hot soapy water and rinse. Give them lots of time to dry. If you have a compressor, blow into the crevice between the center and outer sections of the wheel. A lot of moisture and dirt will come out the other side. Wipe the wheels with some type of pre paint wax and grease remover. Give plenty of time to dry. Blow out the crevice mentioned above of any of the wax and grease remover got into it. Apply the primer. Follow manufacturer's instructions for drying times and top coat preparation. Spray the color following the manufacturer's instructions.