I just went across country in my 08 JkU with 3.73 and 35s. 
When I kept it under 73 mph it would run @2,900 rpm averaged 11.3 mpg. 
When I kept it at 81 mph it would run 3,100 rpm average would be 10.9 
Looking at gears now. Doing 43mph by the time I hit the top of the hills not good. 
Never did any long rides so I thought I was ok for now but I was wrong. 
AMen
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