My buddy broke his arm when the bead blew on the 16 inch tire he was putting on the 16.5 wheel. They where very stiff sidewall tires and the wheel was old and we didn't realize that it was a 16.5. He reached to take the air chuck off of the valve stem because it didn't seem right to him and it blew and broke his arm on the way by. Do you like pain?

 

Don't do it. Not only is the diameter of the bead different (obviously somewhere around .5 inch), but the bead profile of a 16.5 inch wheel is different the the bead profile of a 16 inch wheel. A tire designed for a 16 inch wheel will have the correct bead to correspond to a 16 inch wheel. Since the bead profile shape is different a 16 inch tire WILL NEVER SEAT PROPERLY ON A 16.5 INCH WHEEL. It' is like trying to shove a square peg through a round hole.