Rear Versus Front Tire Widths

My father (long gone now) had a couple of cars that for a while he ran bigger tires on the back than on the front. OK, looked good, etc. Except that when the tires got 4-5 thousand miles on them, he rotated them - big tires on the front, small ones on the back. And if the big front tires rubbed the fender lip on turns, a hacksaw took care of that problem. It's a wonder I still have hair. . . .