The tire manufacturers charts shows what is necessary to support the given load and achieve good wear. In my opinion this is part of the story, the other part is how the truck handles. Some tires (Michelins for example) have a very limp sidewall, and the truck will handle much better with the tires inflated more than the chart shows.
I would inflate to the tire chart or door jamb as a minimum, but then experiment above that up to the max listed on the sidewall and see what you prefer. There may be a slight reduction in life at higher pressure, but they seem to last a very long time on a dually anyway.