problem with 5 Slot wheels and drum brakes

That used to be a common problem with flat backed wheels. Most of the chrome slots fit that category. The back of the wheel would contact the lip of the brake drum or the balance weight on the drum and when the wheel was tightened it would oblong the drum. There used to be a company that made 1/8 aluminum spacers to get around the problem. I made my own with a jig saw and metal blade and a drill press out of 1/8 aluminum sheet metal. A set of spacers should cure your shimmy and shake......