Switching from 11R 22.5 to 295/75R 22.5 Volvo VNL 670

Because you are using the same torque and power to turn a marginally smaller wheel, if you keep your rpms the same as before you gain what feels like about 15-20 hp but will go 3 % slower

 

I just went the other way, from lo pro 22.5's to 11R. FLD120, 13 speed with 4.10's. I would run 65 mph at 1650 rpm. Dropped my rpm's to about 1550 at 65, which actually made everything run smoother. Have just a little less pull on a big hill, but not huge. Really like this set up. I think you going to the lo pros on your setup would be a toss up. You're going to gain some pulling power in the hills. Won't be huge, but may see it. I've only run one fill up through these tires, so fuel mileage is still up in the air. My all time is 5.9 mag. Lately been less because we've been windy. Had been around 5.5. Last fuel up was 5.1. We'll see what next week brings.

 

The others covered it. It's minute at best, and I probably shouldn't have mentioned it. But it's just a byproduct of switching tire size, as much effect as changing gear ratio would have.

 

Depend on trans ratio, but if .73, I would think just above 1500 @ 67. I used to have the formula memorized to tell you exactly, but those days are past.

You can probably find a calculatot online

 

In the same rpm (3% lower speed) you will feel like you have more power yes, but if you want the same speed as before up the same hills you will be running higher rpm

 

To expand, you never truly "gain power" with no tradeoff, if you want the same speed, your rpm goes up, if you want the same rpm, you lose speed.

Depending on your gear ratio prefered speed and if you found your engine's "sweet spot" before or after you may gain or lose mpg

I had tried to post a longer explanation before to counterbalance cdemars experience since he didnt drop to "normal" lp 22.5s but the absolute smallest lp 22.5s available.

He already had the sweet spot for rpm on his engine and it matched his desired cruise speed, then he had to raise rpm to meet that desired mph and as a result lost mpg, his hill pulling capability increased, but at a mpg cost