Your 4runner's suspension is very well-built...overbuilt. For the 3rd gen 4runner, the upper and lower control arms of the front suspension are boxed, rather than just stamped steel (common in American trucks/SUVs). Boxed arms are very strong...forged steel arm is the only thing that is stronger (seen in the new Range Rover for example).
The control arms for the rear axle is all of rod-type. Therefore, they are very strong.
The wheel bearings/housings are no weaker than that of American 1-ton truck.
What does this all mean? Your 4runner is plenty tough to handle the LT-rated tires. In 265/70/16 and 265/75/16 sizes, the load ranges are usually C- or D-range. (Note: in general, C-range=6 plies; D-range=8 plies.)
BFG AT KO tires are the only AT tires that have triple sidewall plies to prevent laceration to the sidewall, like when off-roading over rocky areas. Bridgestone Dueler AT REVO tires uses the same sidewall as regular tires.
Hope this helps.