looking to go from stock tires [p25570r17] to slightly bigger ones [lt26570r17]
my question is how it will affect gas mileage and gearing [shifting] especially
while towing. i have an 07 f150 xlt 5.4 with a 3.73 ls rear. my old truck was an 03 f150 xl 4.6 with a 3.55 rear. i went from stock tires [p25570r16] to [lt26575r16] and it shifted alot on hills,and while towing it lost all its power.
any advice out there?

 

That's a pretty small change, your overall tire diameter would increase by .55 inches. I really doubt you would even notice it.

 

I agree.