Sorry, NMT, but I have to disagree. You can't say that one pressure is the best overall for any and all tires we could put on the trucks. That just doesn't make sense. Plus, when I got my BFG's they specifically told me to keep them at 40psi. They have a max pressure of 80psi (on the sidewall as you suggested), and for the weight of the truck, 40psi is what I would need. Less than that (36 from what you say) would be too soft. Realistically can I tell the difference between 36 and 40? Maybe, maybe not. But underinflation for the weight of the vehicle will cause uneven tire wear.

So again, it depends on the tire, the ratings for your tires and where you are driving them too. For example, if you're going in sand or terain that is exceedingly soft, lower the pressure. Some go as low as 12-15psi. Then pump them back up for the road again.

And we all know that the the auto manufacturers "recommend" a pressure that would be considered underinflated so you'll have "better" ride comfort. Why else would the auto manufacturer recommend a lower pressure than the tire manufacturer?