If you don’t fly often, or are just a plane (har har) inconsiderate person, here is the correct way to place your bag in the overhead bin: Short side facing out, shoved straight back and wheels out so that the upper, malleable and smaller part of your bag hugs the tapered part of the bin against the wall.
See how cute they look together all snug in a row? If it doesn’t fit like this on a full flight your bag is too big.
Below is the wrong way. Placing it wheels sideways (lengthwise) hogs up way too much bin real estate and is considered rude. Also a faux pas is laying jackets, purses, and manpurses in the bin before everyone has had a chance to grab space.
Note the “right” bin contains FOUR bags, and the “wrong” way only allows room for two. (Until some Zone 4 boarder needs to make room and turns your oversize bag 90 degrees.)
My Eagle Creek bag that I love so much fits perfectly as a medium to large size roller bag, although tight in the center bins of a 767. Some larger bags will not fit with wheels against the wall, but flipping it around (like below) fits perfectly snug. Try yours!!