I installed a new set of Hankook H724 185/75/14.
10% drop in RPM
Mileage went from 50 mpg to 55 mpg with cruise control on in open road.
55 mph/hr 2500 rpm
60 mph/hr 2750 rpm
65 mph/hr 3000 rpm
Engine does not like to pull very well less than 2500 rpm as torque drops off real fast below this point.
I do not believe I could gear it up any higher than this.
Tire size is also maximized
Any thoughts on this idea?