As far as tire size difference.
The diff between a 265/70/16 and a 265/75/16
70 = 30.606
75 = 31.649
or 1.04 inches.
When you figure that in half (half above and half below the rim) you only need an extra half inch of clearance. Air pressure will make that much.
Of course this could vary slightly if rim width is changed
