Can't remember where I read it, but apparently now that the wheels are all nice and shining, you should put a few coats of car-wax on it to make it more resistant to dirt and other corrosive substances. Might help keep it clean longer. just an idea, never actually tried it myself...

I was told from a great wheel polisher out west a slight coat of PAM cooking spray will deter a LOT of crap for a while between polishes.