I filled in the weights of cascade bob in to my motorhome-tire-pressure calculator part 3 , though I know its a travel trailer, 5th wheeler or whatever thing to tow . But stopped when filling in the loads when I saw the rear left of 2800 lbs . Is that realy so or a miswriting?
If realy so it shows that for tandem axle it yust the same as for motorhomes , that you can have crossed weight differences .
Mostly that is courced by something heavy ( or more things) on that left rear behind the axle. this lifts up the front axle on that same side.
Best would be then to try to shift some heavy load to front right if possible, for more even loading over the 4 wheels.
But otherwise base the pressure on the heavyest tire so here RL of 2800 lbs.
Hoping the tire is allowed to bare that load.
You stil did not give the loadrange ( D to H letter) so we cant determine the maximum load of this tire.
This PDF of Goodyear shows at botom of page 1 that you may overpressurise the AT pressure by 10 psi.
B.When higher pressures are desirable to obtain improved operating performance.
The combined increases of A and B should not exceed 10 PSI above the inflation specified for the maximum load of the tire
wich is that 80 psi for instance for a E load tire. So its allowed to use 90 psi for such a tire.
My idea is that for that 2800 lbs LR you will come higher then the AT-pressure for your tires.
Best is to see if you can find a LT tire with same sises and AT-pressure,and use the maximum load of that tire in my calculator .
Then if the outcome is AT-pressure +10 psi , use that to be absolutely save.
But this case shows why ST tires are adviced at their maximum, because one tire often comes to high loads