^^^ unless your rims is chrome most likely it painted with clear coat.. Not sure which wheel you are running.. but any silver finished wheel is painted.
i washe them good two nights ago and most of it comes off...and i talked to someone who details cars and he said to use some sort of acid??? its used to clean rims, but make sure you wash it off and dont let it sit for to long.
to get rid of all the brake fluid residue use a brake and parts cleaner and rinse afterwards or use a bit of soap...u can find it at crappy t or any parts place...soap wont really do too much to get rid of brake fluid