I was flicking through an old copy of "the golf" magazine the other day and there was an article on a company that specialise in refurbing splitties. It was either nov or dec of last year, I can have a look and post the details of the company if anybodys wants???
In answer to the question, autoglym wheel cleaner or wonder wheels etc if the rims are laquered. If the rims aren't laquered (which I doubt) then good old autosol and some elbow grease
Toby