I myself, do not ever make one wider than 2 inches, but 98% of the time I stick with 1 to 1 1/2 inches wide, that makes a really nice rug that isn't too thick. But if you do happen to have a rug that is just to big for the washing machine :
Mix a solution of soap (whatever you prefer)and water in a spray bottle. Throw the rug over any fence but a chain link works best. Spray the rug with your solution, then spray off with your water hose. You won't hurt your rug and it will be clean.
Eva