I just make sure that I clean it thuroughly every week so brake dust doesnt eat through the thing, then i use the harley chrome polisher on it. looks decent to me still after around 12000miles.
there are some products that can bring some the shine back into the rubber...ask one of the car wash places around you what they use to bring the black back into the tires. as for the rims, try looking if mother's has something for that (mothers chrome polish)...or again ask a detailing place near you
If you are talking about the polished rear wheel, I used to use the mothers power ball mini with the mothers power metal polish. It works great. I have since switched to a chrome rear.