thats about what I lost when going to a LT E on the different 1/2 ton trucks I've owned over the years. I've also tried load D and E on 1/2 ton trucks but always went back to P tires (44 psi on P SL tires and 51 psi on P XL tires).
And one reason (when ordering) I stuck with the 17" OEM P265/75-17 tires/Aluminum wheels on the wifes 2016 1500 chevy.
I did come up with a extra set of four 17" OEM steel wheels and mounted A set of Goodyear LT 265/75-17 load C for muddy work sites and pasture work pulling a 10k car hauler with a 7600 lb blue tractor with a cab. Makes for a tall 11' 8" top heavy load. The steelies and load C tires are heavier resulting in 1-2 mpg loss on highway trips....not so much around local runs around the area.
I'll probably go down to a 275-65 as they are lighter in weight and come in an XL. Lost over 3mpg with the heavier tires.