Look out, 33x10.50x15 bfgoodrich allterrians

[BeaterMan]

i've had those same tires but 235/75/15's for the past 3 years and keep them in the ranger of 30-35 and they are all wearing completely the same on my 99' ranger. the pic definately looks like under inflation

 

[Hahnsb2]

The OP states that the outside edges were being worn off, that would lead me to beleive under inflation aswell.

But claims 5" of tire is contacting the pavement and the pic looks like the center is worn down and contacting the pavement more than the edges. And the pictures of the black marks on the pavement also suggests center contact.

 

[4x4junkie]

That pic looks like a tire that is crowned from having been underinflated for some time, but now has the correct pressure (it's only contacting in the center now).

It IS normal to sometimes see a little bit of the tread edge not touch the ground with brand new tires on the rear, however like was mentioned, the OP stated they were wearing off on the edges more.

 

[JohnnyO]

It looks like only the middle of the tire is touching the road. It might be 10.50 in width like stock, but with the taller sidewalls I think you need a wider rim, like 8". Or run less air until they wear right.
Once you change from the stock tire size, the door sticker is meaningless. The bigger the tire, the more load it can carry and when the truck's weight remains the same that means you need less air pressure.