How much air in the tires? Need advice... First "real haul"

as I'm a memeber of the max pressure club even my ecno box focus hatchback has max pressure in the tires...comes in handy when you get to make a stop out of the blue and pick up 5/6 hundred lbs of semi parts.. biggest thing you'll notice is the ride is stiffer and less squirm from the tires and even if you have more capicity than needed is better than being uninflated in my book