I have a few questions for you:
Firstly, the tire height in inches is not the one that BFGoodrich provides, nor does the math work out.
BFGoodrich says the tire has an overall diameter of 33.3" on a 7.0" rim: http://www.bfgoodrichtires.com/assets/pdf/mud_terrain_ta_km.pdf
Logically, using a wider wheel will reduce the overall height given the same tire pressure.
Mathematically, the tire is calculated to have a diameter of 33.1".
This isn't really a big deal, just a discrepancy.
Secondly, when you say the 255/85 offers improved traction over a 33x12.5 or 285/75 size tire, I must ask where you get the support for this claim, other than experience basing your assumption.
In physics, friction, and therefore traction, is not influenced by surface area. The only factors are the materials and the normal force, or force resisting gravity in a direction perpendicular to the surface.
The 255/85 has a higher load rating, indicating that it is probably of a sturdier tread compound than that of the 33x12.5.
I like your website very much, and it's incredibly well put together.