Questions about lifting and gear ratios

[AUChevyGuy]

I've gotten a wide variety of answers and I'm hoping to get some help in figuring out what is correct. I have a 2009 Tahoe LT RWD and I've got a Rough Country 3.5" lift and 33" tires on stock 20's. My fuel mileage went from 23/18 stock to 14/11 with my current setup. I'm about to go to a 8" lift with 35's and I was nervous about what that would do to my gas mileage. I know anytime you go bigger you're going to lose mpg and I'm ok with that I was just surprised that it went down that much with the little lift I have. I was talk to a guy that has a 12" lift with 37's and he switched his gears to 4.56 and he gets 18/15. My Tahoe has 3.08 gears stock which is why I'm assuming my mileage is horrible. When I get my new lift and tires on should I go to 4.10 or 4.56 gears? I'm assuming either will increase my mileage as well. Any help is appreciated, I'm ignorant when it comes to this because everything I've ever lifted before had at least 3.73 gears so it wasn't as noticeable when I lifted them.

 

[01Konvict]

If you go to 8" 35s go with 4.56. Best combo for tire size. Really only need 3.90-4.10 range per calculator but the increased tire weight needs the 4.56 to drive normal and get gas mileage back up

 

[AUChevyGuy]

Awesome thanks! Any ballpark idea of what to expect on fuel mileage if I go to 4.56 ?

 

[01Konvict]

Probably back to 18/15 or 17/14

 

[LTV Chaos]

Would be interested to hear how much the gear ration swap out runs? On my Jeep it cost about $3K. Would have to crunch the numbers to see how soon to recoup the cost on gas mileage. Of course if I tow my wife's minivan cross country I might not be too worried about recouping the cost, just being able to tow.

 

[MichaelSE]

Would be interested to hear how much the gear ration swap out runs? On my Jeep it cost about $3K. Would have to crunch the numbers to see how soon to recoup the cost on gas mileage. Of course if I tow my wife's minivan cross country I might not be too worried about recouping the cost, just being able to tow.

I got a quote from a local shop when I was considering switching to 4.10 gears. It was around $2800 IIRC including parts and labor.

 

[LTV Chaos]

That's not too bad. Thanks for the feedback.

Pete