My 2004 Silverado Ext cab Z71 came with 265/75R16 rated for 35psi as the door post label recommends. After 50K time for new but don't really need off-road. I put General Grabber HTS on the rears, made for 44psi, and will do the front in a week or so. Back end handles fine and does not jump around at 42-44psi. Is there a true safety design reason for using 35psi tires, or are we talking comfort for the average driver? I have been trying to research this and I'm leaning toward the comfort angle.