If you're running them at 80psi on an mostly empty truck, it's no wonder your tire life isn't so good... You're asking a very small portion of the tread that is in contact with the road to do all the tractive work... And that takes the tread off in a hurry.
My enemy is tire pressure monitoring... An empty 3/4 ton truck doesn't need 80psi in the rear tires, and ride, traction, and tire life all suffer for it. Run the fronts at whatever the door sticker says. Run the rears the same, or slightly lower for an empty truck, or add pressure according to the amount of weight you carry. Running 80psi all around with modern tires is pretty ill advised, and doing you no good at all...
OP, what kind of truck? How is it loaded? What pressures do you run, what kind of roads, etc. With normal use, you should be seeing about the mileage they predict out of any tire. Check to be sure tire pressures and alignment are good, and rotate every 5-10k, depending on wear.
??