If I know what I think I know, but who knows what they don't know, just about all load/pressure charts should be the same. The load for a 235-80-16 LR "E", for example, should be the same whether it is a Goodyear or Sailun. That said, look at a load table for your weights, assuming you know the load on your tires. Then adjust accordingly.
But be aware that some brands (Carlisle) highly recommend running ST tires at max pressure. However, I have seen a "cut and pasted" email from a Sailun rep that said Sailun is OK running their tires at less than max IF it is within the load range.
If you are running an un-necessarily high pressure you can shake the trailer a lot and possibly damage the suspension and/or contents. Also the tread footprint may not be maximized. This may be what "Cummins" is getting at.
We don't need to discuss unsprung weight and added rotational weight, do we? lol
Be sure your wheels are rated for the pressure you are running.
