With a P as OEM you must have a 1500 truck.
The P XL is a excellent choice over the LT E for your 1500 truck for several reasons. Keep them pumped to the max sidewall psi. They will run cooler and doing so stiffens the tires sidewalls up and helps with trailer sway issues. They also have much less parasitic drag (rolling resistance) than a E tire at 50 psi.
I keep OEM LT265/70-17 C on the wifes 1500 crew cab 4x4 chevy. When hauling or towing I keep them at 50 psi and air down to 35 psi when not.