I tried an experiment because I was not a believer of high psi equals better FE. I noramlly run 36psi all around and was getting around 48mpg. I bumped up the pressure to 51psi all around (max psi) and noticed an increase of 2 mpg on the first tank... but then it went back to my normal average. I do have to say that my worries in the rain were incorrect. I thought a higher psi tire would be worse in the rain but it turns out it actually behaved better in the rain.

What did I get out of this experiment? I noticed that handling got better as more psi were added to the tires. I noticed no increase in FE.


As PSI heads to MAX PSI (with everything else being equal):

Pros:

Handling improved.
Better handling in the rain.

Cons:

Ride quality got worst. Every bump could be felt and heard.

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FE: remained the same, with a slight edge towards the higher PSI runs. Please keep in mind that I got maybe a few extra miles per TANK not per GALLON. My first tank fluke could have been attributed to my driving style changing to conserve as much fuel as possible.