we are beta testing a wheel visualization tool. It is available off of our home page by clicking Wheel Finder under the 'Other iRate Stuff' Section.
With it, you can check out how different wheels would look on your car. Simply select your make / model year car, then adjust your ride height, and then play with your different wheel options and sizes till you find something you like.
I would be very interested in getting some feedback on this tool. It is rather expensive, and I'm still undecided as to wether or not we want to buy it and integrate it with our shopping cart.
I hope this helps you with your wheel search,