I am of the same thought with you, Mello Mike and CumminsDriver. I guess some folks will argue to not make changes to your truck because the truck engineers are all knowing, then want to play "scientific research" with tire pressure. My bet is the tire manufactures ram millions of dollars testing their tires under various conditions. To imply their charts on their tire pressures incorrect is not "scientific research" in my opinion.
Let there be no question, I will modify just about everything on my truck, including tire/wheel size. That said, I will follow a tire manufactures (not tire store) on the psi.
My bet is that most folks have no idea as to why there is a minimum psi on the 19.5 tires.
Wayne
