You need to be a little more specific in your rim and tire sizes/type.
There are too many variables to accurately determine city/highway MPG after the fact including, but not limited to, gear ratio, fuel of choice, driving habits, terrain, load/towing, other performance modification..... and the list goes on.
Truck was sold today [5/19]. I got an offer I couldn't turn down. I had no more need for a pickup so I cut it loose. About to purchase a '14 Jeep SRT8 this week.