The compatibility of the rims is all to do with the file sizes, I mean in KB.
You cannot replace a car's rims with a file which is bigger than the original, you can, however, replace it with a file smaller than or equal in size to the original.
At the moment I have the Caterham R500's rims on the Corvette Stingray '69. Sounds like an odd choice I know, but they're just simple 8 spoke wheels which really suit the lines of the Stingray.
The Caterham R500 isn't currently in the game, but its rims are there.
The file-size theory also applies to the sounds. I've got the Audi A6 sounds replacing the Audi RS4's sounds, this just makes it sound a little beefier and a little louder.
I also have the Noble M12's sounds on the Saleen S7, it sounds just the same, but it's considerably louder, so you can actually hear it. Well, it has a different horn now, lol.
Hope this helped.
EDIT: Here's a pic of my Stingray with the R500 wheels!
http://i191.photobucket.com/albums/z245/matt88sco/20070826194413.jpg