The RVIA RV Class definitions as posted above by mumkin have been repeatedly posted on this forum many times. Nonetheless people still choose to contribute their own two cents worth. The RV marketing people are the ones that contribute to the confusion by using the "B+" alternative that has no real definition but I guess they think it will help sales of their small Class C by implying smallness or something. A so called B+ (there is no definition for a B+) is simply a Class C on the small end of a Class C's length range. It comes up in this forum a lot because posters do not use the correct forum for their RV's class when posting. You won't find B+ mentioned anywhere on the RVIA website.