Join Date: Oct 2017
Location: Adirondacks, NY
Many dealers will not do it.
Some will, It is a change in the BCM that can be done if the tech is willing.
I had my '18 done, and now my 2020 is also lowered.
I run 48-50psi rear when not loaded and 65 front.
They are instructed to not do it so as to protect themselves for liability reasons, because we are not smart enough to inflate tires when running heavy loads.
2020 Sierra AT4 3500 Duramax
2018 Denali 2500HD L5P Derringer equipped
2018 Montana 3811MS Legacy 16400#2900pin