55 psi? Are you out of your mind?
My 32x11.50-15C BFG ATs have a max pressure of 50 psi, but that's only for when the tires are supporting 2530 pounds apiece (load range C).
Your 265/75-16D tires are max 65 psi when supporting 3042 pounds apiece (load range D).
The Xterra doesn't weigh anywhere near 10,000 lbs, much less 12,000, so that kind of pressure is WAY outside what is called for under any conditions the tire/vehicle would encounter. Even if you loaded the X down with a bunch of crap, you'd be hard-pressed to put more than 3000 lbs. on an axle, or 1500 lbs. per tire.

By running such high pressures you're just asking for poor wear, HARSH ride, and reduced contact patch and traction. I got well over 65K out of my first set of 32x11.50-15C BFG ATs running at 30 psi, with very even wear across the tread. If I ran 40+ I would have worn them faster in the center of the tread and not gotten as long a useful life out of them.

Wake up!
Brent