Well, for a primo job you need to take the wheels to an abrasive blasting place, then primer with that expensive green etching primer, then shoot with some nice silver paint. this is all done everyday by pros but you are looking at 3 hundred minimum.
a cheaper route, clean the old wheels really well with wheel cleaner and a soft wire brush, rinse, sand the worst spots with super fine auto sandpaper, like 600 grit, then try to find Wurth silver paint in a rattle-can. Cost? about twenty bucks.