[kingdaddy]

Hmmm...if I interpret your weights correctly, sounds like you have about a 12k lb trailer with a 8k lb truck. So with 2k lb hitch weight you would have 10k sitting on the axles. Does that sound right?
I know your truck has to weigh close to 8k (without the trailer weight of course) so if your whole rig weighs 20040 then the trailer total weight is around 12k. With 10k sitting on the axles, you might conclude that 2,500 lbs is on each of the four tires. But that may not be the case...depends on how the trailer load is distributed side to side and front to rear. For example, my trailer is very well balanced side to side, but carries a bit more weight on the rear axle due to the floorplan (rear bunkhouse with double rear slides) and the fact that my trailer sits a bit nose high.
Bottom line, sounds like you would be just fine with a set of BFG Commercial T/A in 235/85 16 rated at 3042 lbs capacity. Great tire for the price...lots of folks using them (myself included) and they get great reviews.