I have a 2016 and live in CO (Durango) and spend a good bit of time off-road. I have a 2.5" front/1.5" rear lift, RCI skids, sliders, SSO slimline front bumper and winch and APEX steel rear bumper (so I am carrying alot of weight). My highway mileage is around 17.5 but I don't have any power issue going up mountains on the highway or on trail. I like the extra width and height of the 285s and have a small front rub when backing up at full lock (hitting mud flaps).
I am running K02s and I moved up from the 265 K02s when they wore down at 80k and now my speedo reads correctly