You can't really go wrong with the manufacturer’s recommendations. If they say at X lbs run Y PSI then you won’t damage the tire and you should get the best compromise between gas mileage, tire life and comfort from your tires. You may get better mileage from running overinflated but you’re likely to wear the center of the tire more quickly and ride quality will suffer.
We are roughly at a “fixed load” and that makes it easier to take advantage of choosing and maintaining the correct pressure for the tire based on load.
http://www.bfgoodrichtrucktire...eInfo.do?tread=DR444
Go here and you can see how much pressures can change based on the load for the 275/80R22.5 DR444.
16,380lbs per axel / running duals = 70psi while max load is achieved at 110lbs
I think this is the best advise you can get...right from the engineers that build them.
But thats just my opinion...there will be more.
Rad