Steve, I agree with doall. I have a 5' box and a 5-1/2' box that I've had since before I bought my TC45D. I'd love to have a 6' or 7' one, but have just never spent the money for one. A blade wider than your rear tires will allow you to cut into a sloped grade beyond your tire width. The only way I can do that with either of my blades is by backing in at an angle and that is less than optimum. If the blade sticks out beyond the wheels, you can shave off with multiple passes in forward or reverse.