Rims and spokes are likely chrome, As for what is what pull out the old magnet, if its chromed, chances are its also steel, and if its aluminum the magnet wont stick. Highy alkaline degreasers will etch aluminum, which is bad, so stick to stuff made for general degreasing, and products that are safe for rubber. Also nothing too crazy on the paint in terms of chemicals either, or your going to end up stripping off old paint.
Look up Caswell plating, they have a ton of products made to polish aluminum, adn chrome and such, I purchased thier aluminum polish kit and was very happy.
Oh ya and elbow grease mixed with a few beers, is usually the most effective cleaning product!!
