We flew NW/Delta from DTW to ORL in June. Our carry on like yours exceeded their requirements in height because of the wheels. I was worried before we left, so I asked my parents if we could borrow one of theirs because they travel a lot. They brought 3 over and we measured them and not one met the requirements! We just went ahead with ours with the idea that if it got rejected we had plenty of extra time to get it checked. They had one of those plastic sizer things in the airport, but I didn't see anyone using it. Even with the wheels our bag was short enough to stow correctly in the overhead bin. (I do think next time, though, I'll just bring a backpack and avoid the whole overhead bin hysteria...) Good luck!