Rims or wheels?

Do you refer to the entire metal part of the wheel assemblies on cars as rims or wheels? I always figured that rims was a colloquial (slang) form of the metal wheel part used interchangeably with wheels. I know several veteran mechanics who use the word rims as well. I understand what the dictionary definition of rim is (edge, outer part), just I always figured the word was just an auto industry's slang usage.