Can someone do a basic breakdown for the fuel economy difference between 2 identical rubicons with the only difference being rear end gears, 4:10 vs. 5:13?

Is this even possible to calculate? Reason I am asking this is I have read I can achieve better MPG if I re-gear. Is this true, how would I calculate the answer?

Thanks for any and all answers!

 

It is benefitial to regear with a larger tire. I would not recommend regearing a stock Jeep. Your mileage would be worse with stock tires and 5.13's.

 

I guess I should mention I am running 37'' tires. I am just trying to justify the cost for gears on saving gas. Maybe this is just a wrong thought.

 

37s and 4.10 gears? iwould just about be ready to lay down a C note that you'd get better mileage with 5.13s, but I don't know how you drive. No way to calculate this, because there are so many variables involved. Getting all that weight rolling with 4.10s has to be a chore for that Jeep compared to stock. Regearing would bring back the leverage, and likely improve mileage. I have to end with this........if mileage is really what you want, go get a Prius.

 

Thanks and no thanks! The whole point is not to have great gas mileage, it is to justify the cost of re-gearing using fuel economy as leverage.

 

Thanks, best answer yet, but as i side note, I average 14 with stock 4:10's and 37'' tires.

 

Hypothetically, let's say you had 5.13's. You'd get decent mileage around town with those big beefy tires, but then you'd be driving at 3000 RPM all over the highway at 62 MPH, give or take. So you'll get 15, 16 MPG around town, and 12 or 13 on the highway.

On the other hand, let's say you go lower. 4.10's. Highway is good, around town not so good.

Mathematically:

$1200 for gears. $1.55 for a gallon of gas. You could buy 38 fill-ups (20 gal a pop) of gas with that money. 38 tanks, 300 mi/tank, 11,400 miles.

In short, I don't think it's worth the money. I would do it anyway, but it doesn't seem worth it. You have to compromise on both sides; less than stellar acceleration, and driving at a little higher RPM on the highway. That being said, if taking a lot of strain off the engine is worth it to you, then it's worth the money.

 

With 37's 5.13's would be a good fit for your Jeep. Not just for gas reasons, your truck will labor more with the lower gears. In every aspect the gear change is definitely worth it.

 

Thanks a lot for the last two responses. Very Helpful!