Well, I'm sure just about everybody knows this works since Randy's Tuff Wheel experiment! So I bought some Royal Blue Rit dye from the grocery store and tested it on some old, beat up white pedals. Just let them boil for awile in the stuff, but it didn't even take awile for the dye to adhere to the plastic. Royal Blue is NOT a color I would actually use though, turned out kind of gross. But the pedals had dirt on them which I couldn't clean off, so I knew no matter what they'd look ugly upon taking them out (Different shades of blue, darker in dirty spots of course) But yeah, dying plastic works and it'd most likely kick butt using colors you couldn't go wrong with (like black for example, or darker colors.)
I'm sure Tuff Wheels would turn out sweet, using NOS Tuffs since the entire wheel would be clean and the same color, but I'm a chicken right now so I'm not going to try for perfection and risk ruining a set. I wonder if there is such thing as a pro Rit dyer..LOL.

This cold dye method another member was using would probably be better for the Tuffs since the plastic basically absorbs the dye quickly when being boiled, and I'm sure the wait would be well worth having a beautiful outcome. Let us know how it turns out!