Rit will work on ant plastic or nylon wheel. to get "black" takes time and patience though. you will want to boil water, remove form heat, add rit dye, throw the wheels into the dye mixture for about 45 minutes, and repeat the process, otherwise you end up with a washed out purple color.

Black is te only color that requires a double dip and 45 mins each time. other colors take much better.