Im getting a set of 305/70/16 tires for my 91 3/4 ton 4x4. From measuring it looks like the tires are going to rub the front bumper on the bottom. It has 265/75/16 tires on it now and these new ones will be an 1 1/2" bigger in diameter, and 2" wider. What are my options? Im thinking about moving the front bumper forward 1 1/2" just to be on the safe side. Has anyone done this before. I dont really want to cut the bumper corners.

 

Most people just cut the bumper on the bottom and kind of round it off so it follows the contour of the bumper but makes room for the tires, you will also have to cut the bottom of the fender at the back of the tire.
Hope it all works out for you. I wouldn't move the bumper unless you were relocating it for a body lift. (relocating it higher)