Ok... so what are the stock tC wheels made of? What kind of finish is on them? Right now I'm washing them with the same stuff as the rest of the car, and then using a microfiber towel to get the dirt (and brake dust) that remains off. They look pretty good, but I'm wondering if this will be enough over time. Also, is there something that I should be using to protect the finish on them? I use Zaino on the rest of the car, but it would be pretty hard to apply to something like the wheels. Advice? What is everyone else doing?

if you use some sort of tire gloss make sure you wipe the excess spray off the rims. prevents it from eating away the clear coat. I sometimes wax the rims on my cars (silver painted rims)pretty much just wash the wheels and get rid of the brake dust.

Yeah... I've stayed away from that tire stuff because it's all greasy and I don't think it does any actual good - just for looks, which I'm not huge about. I might try and clean them really good and polish them, but with so many little nooks and crannies, I'll probably just stick with washing them and wiping off the dust as it comes.

i usually put a good coat of turtle wax on my rims before winter hits, i have 15" gunmetal motegi mr7's.
here, someone told me this stuff is pretty good too
http://www.tirerack.com/accessories/wheelwax/wheelwax.jsp

i agree.. you can put some wax on the wheels.. it will protect them.. i've done it before and it does work well..