How do you adjust level on air ride suspension on steering axle on peterbilt?

There are two bolts holding the leveling valve in place, with the one on the bottom being more oval shaped...rotate the leveling valve counterclockwise to raise it, and clockwise to lower it. To calibrate it, you'll notice a small hole in the leveling valve arm, behind the hole for the bolt. You take a Golf tee, stick it in there, and adjust it until it lines up with the matching hole in the leveling valve itself.