depends how dirty they are. do you ever clean them? i have a nice thin brush i use to get in the tight places. just use soap and water but scrub them. brake dust is nasty. i had a bottle of armor-all wheel cleaner sitting in the garage for 6 months that i forgot about. i sprayed some on and it seemed like it was not doing much. than i shook up the bottle a lot and it seemed like brownish stuff was coming out. thats odd. i hosed off the wheels and they seemed even brighter than before. hmm, maybe this wheel cleaner stuff really works. they look great now.