The tire pressure is dependent upon the exact tire size (different with different wheels also, btw) and the empty-wt versus load-rating of your exact model truck with it's factory options. Two otherwise identical appearing trucks may have different recommended tire pressures for those sort of things.
Our 2012 2500 has a light load button on the dash and when it in it lights up and the tpms is in light load but if the light is not lit the tps is in he heavy mode an if the tire pressure is not correct he low pressure light comes on in he instrument cluster. Dealer tells me they have constant problems with the tpms system.
It is a 5lb leeway +/- But most are set off with as little as 2.5lbs. Inflate them to regular manufacture recommendations and all should be good. The BCM (Body Control Module) stores the information and it can be adjusted just takes someone knowledgable and some time (about 2 hours) to do all 4 tires (5 if the spare has a sensor) it is not all that hard but most dealerships won't do it.