In his original post, he said that the original paint is coming off. It's obviously lost its bond to the aluminium rim. Why would you want add perfectly good paint on top of paint that is already coming off? The new paint will just come off on the back of the original stuff.

He needs to use a chemical-stripper to remove all traces of the original paint. Aircraft stripper works well. Then clean off the surfaces very well and sand with 400-grit wet. Now, the most important part is the primer, and the wrong primer was used originally, which is why the paint is coming off. You need to use a zinc chromate etching primer on the bare aluminium. Look that up to see why. This isn't a filler/sanding primer that most people are used to. It's sole purpose is to chemically etch the aluminum and provide an adhesion-friendly surface for the next layer of paint. In this case, the next layer should be the regular filler/sanding primer you're used. to.

Sand that and apply your favourite flavour of auto-paint. Not rattle-can stuff, but real 2-part auto paints that they mix in the back and bring out in cans along with an activator and reducer. There is a HUGE difference in the quality of even the bottom-of-the-line auto-paint versus the most costly rattle-can paint. Not to mention the auto-paint is cheaper for the volume and area covered.