Guys its what the truck saies not what the tire saies
I will go ahead and call you out here, unfortunately you are incorrect.
The vehicle recommended tire pressures are based off of the same rating of tire being installed that came from the factory which should be a C or P rated tire (can't remember which). So, if the OP had factory rated tires, you'd be correct.
That being said, the OP sates that the maximum tire pressure rating on the tire is 80 PSI indicating that they have an E rated tire. These are usually reserved for larger trucks and are a bit overkill for the expy but hey, they work.
Tires require a certain minimum pressure to maintain structural integrity of the sidewall or else they will break down faster and risk the possibility of sidewall failure (blowout). Just give your local reputable tire dealer and they'll be able to confirm this...
The minimum pressure for a C rated tire is right about 30-32, for a D rated tires it about 40-45, and for E it's about 50 PSI. Anything lower than that on those is risking heat buildup and blowout, especially on long trips and ESPECIALLY in hotter climates. MANY more failures occur due to underinflation rather than overinflation. The only thing that is negatively affected by overinflating a tire is a higher rate of treadwear and an uncomfortable ride.
OP: PLEASE do not run anything lower than 50PSI in your tires, 46-47 at BARE minimum, yes it's going to be a bit more uncomfortable but you're not running the stock rated tire and therefore need to deal with those consequences. Upside is it gives you the possibility to have less rolling resistance and therefore slightly better mileage.
