Tire size question on my 67 C10.

[johnymac]

Now that I realize that my truck has a 5 1/4" front and 6 1/4" rear drop. I am going to change to a 4/6 drop in time. The truck currently has 255 70x15's all around.
I thought that would be good for rotating purposes.
I see out here online may trucks seem to run 245 in the front and 275 in the back.
Does anyone know if my truck would handle better with taller tires in the back, or is there another reason for this?

Thank you.