I know this is probably a very stupid question but do flaps come in different sizes, or is it a "one size fits all"? I have 30x3 in front and 30x3.5 in the back and they are wooden felloe wheels. I know flaps are a very touchy subject but I don't see the harm in them and I want to be sure about the size before I order them.
Yes, they come in different sizes:
Simple answer - 24" on the front & 23" on the rear.