Purchase tire chalk, yellow crayon stick at a auto parts store. Check your tire pressure. Say it’s 45 psi for example. Draw a line across the tread pattern. Pull forward 100’-150’. See where the mark wore off. If the center is rubbed away the pressure is to high. If the shoulder rubbed off the pressure is to low. Adjust accordingly until the mark rubs off evenly. This is the chalk method and about the only accurate way to adjust pressure. It will vary with loads as well. Say like camping with a cooler, gear, food, toys, etc.