Badunit
Well-Known Member
I regeared my 2015 Cummins Ram from 3.42 to 4.10 and saw no decrease at all in mpg, even on the highway at 80-85mph. It sure made a world of positive improvement in drivability, though. It was a dog before regearing, now it is an absolute pleasure to drive. Maybe this is off the mark as a comparison but I thought I'd throw it out there. According to my gearing calculator, a JT with 37's and 4.10 in 8th turns almost identical rpms as my Ram. I don't know if going a step further to 4.56 was/is necessary for a diesel JT to perform at its peak but it sounds like you are enjoying it.
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