I am one, and I don't know.
I generally refer to people who can stand and walk as uprights. Garry, my favorite upright, suggests "downright." Downright cute -- maybe, downright fascinating -- wishful thinking, downright confused about what to say when talking about people who use wheelchairs -- true.
I have seen several terms -- wheelchair community, wheelchair users, riders, sitters, rollers -- but lately I have been using wheelers, the term used by 360, an e-zine for the wheelchair community. I think it's pretty clear and I hope it is not offensive to anyone. I used to say "wheelchair bound" and then read that is not acceptable. I don't have a problem with that one, but someone does.
Today's society, at least in the U.S., is so politically-correct conscious, we are almost afraid to talk about anyone. The Canadian state department has published a guideline for terminology use. A guideline is also available from the Media Diversity Institute in London, working with vulnerable groups.
There are several terms that work, guidelines for using terms in the media, and probably some terms most of us don't care to hear. Remember, people in wheelchairs are still people.
What do you call a wheeler?