MPG shift with slightly bigger tires?

I’m running 40 psi on my new KO2s and am happy with that pressure.

 

Most of it is 2 lane 40-55 MPH roads, with only a couple miles down the freeway. Since my freeway commute is so short, I park myself in the right lane (anything over 65 mph and my mpg goes down). In the morning, the computer will say my trip average would be 21-22mpg (people seem to want to drive in the morning), on the way home it says 17-19 mpg depending on traffic, traffic lights, etc. At the end of the week, the tank average week after week has been 19.5-20 mpg. If I speed too much, it drops my average very quickly.
When the truck was stock, I had no problems getting another 1-2 mpg on average.


I can average 16 mpg so quickly and easily if I'm not careful.

 

Lol. You revived the thread only for people to respond to the OP or other's old comments. There definitely are ways to recalibrate everything for use with bigger tires. I've never done it as I don't think it's worthwhile. You actually rack up miles at a reduced rate when you upsize tires which in the long run has literal monetary value lol albeit insignificant at best. Maybe someone else will chime in with what they used but a simple google will get you a handful of devices that will do it.

 

I use Hypertech Calibrator. It works very well, but wasn't cheap. I figured it's worth the cost of avoiding a speeding ticket

 

Very nice rig Mikeybuck. Thanks for posting photo.
I'll be doing a long road trip this fall and wondering where c-rated tire sweet spot is that won't hurt the tank to badly on the freeway. It's probably a wash though going from a 265/70/17 to a 255/75/17...?

 

Yes but a significant part of it is that without speedometer calibration, the truck things it hasn't traveled as far as it has so the MPG calculation is incorrect and lower than it actually is.

 

Just look at the over all weights of the tire. stay away from those 50lb tires.
Plus at the time, my 255s was cheaper than the same brand, load, etc 265.

don't forget to check out the 265/65/17s, might be my next tire size.