Step back for a second and think about what you want.
Do you want everyone on the road to see your calipers?
Paint a bright obnoxious color. Red, Yellow etc Tell the cops I said hi.
Do you want them to blend in with the wheels?
Paint something close to the wheels you are choosing.
Do you want them to be invisible so that people look at your wheels instead of the calipers?
Paint them black. They hide nicely that way. This is always my personal choice. Looks better than rust or oxidized aluminum and doesn't attract attention.
