The actual cold pressure will depend on the axle rating and the tire rating. When doing PM Inspections, in my technician incarnation, I would always check the axle rating sticker on the door jamb of the truck to see what the recommended pressure requirement was for that specific unit. Check for the sticker on your truck and set the tire pressures accordingly. The sticker is usually yellow in color and has the name of the "Completed Vehicle" builder (usually the Co. that installed the freight body) on it.
There are also pressure/load ratings molded into the sidewall of the tires that show load capability at XXXpsi in either single or dual application, check out the fine print located near the edge of the rim.
Rex