A wheel is comprised of 3 parts: RIM, HUB, and SPOKES. By calling them a set of "rims", you're referring to the wrong thing. It's WHEELS. Several people try to argue this concept and claim it doesn't matter, when in fact it does. If and when you move into TRUE high quality custom parts and plan to refer to items as the wrong thing, you will end up buying the wrong item. Call Volk, Enkei, Weds Sport, etc. and order a set of rims and watch what you get in the mail, you will get replace RIMS, which is the biggest advantage to a 3-piece wheel.
Here's a fantastic example to read:
Notice at what point RIM is referred to in the article. This is a dry carbon fiber wheel or an option to have a dry carbon fiber hub with aluminum rims.
Consider yourself educated and please use the proper terminology and en grain this concept into your peers.