Well those rims you photoshopped on there are SC rims which i particularly don't think look all that great on our GS's, but some that I've seen that look pretty good are 3GS rims and some people can pull off the IS rims and make em look good. Also I once had someone photoshop the new IS-F rims on our car and it looked pretty cool. Those are all OEM Lexus rims and would be anywhere from 18" - 20" ...

Now by all means if you like how the SC rims look and you can get them for a good price, don't hold back, it's still a step up man !!

Good luck