Are they load range "D" or "E"
How much does your truck weigh?
What is the weight on the front axle and the rear axle?
Are you driving it on the highway, around town, or off road?
What speeds are you expecting to hit as your maximum?
There are a lot of variables that make up what pressure you should run your tires at.
My M1123 weighs 7k lbs empty. 3360 one axle and 3640 the other.
I have MTR load range "E" and I'm running them at 30psi fpr the last 1k miles at speeds up to 75mph, and with a couple thousand extra lbs of weight the last couple hundred miles, including a trailer.