gearing for gas mileage?
- Thread starter YAEGER83
- Start date
JKAnimal
Caught the Bug
I have a 2012 running 32s and stock suspension, manual 6-speed with 4.10 ratio and I am only getting about 14 in town and 17-18 on the highway depending on how I drive. Just as a reference point for you. I think typically the lower gearing is less fuel efficient. (someone please correct me if I'm wrong.)
if you're referring to a higher ratio, it can be less fuel efficient if it's too high a ratio. this would cause your rpm's to run a higher range at highway speeds and that would burn more fuel. running big tires and a ratio too low for them will cause you to burn more gas trying to get up to speed all the time.
it's hard to say for sure but, i would think so. we're running 37's on our 2012 with 4.10's and find it to be not so bad. either way, i would just do it and if it really sucks for you (because it is subjective to each person), you'll know what to be saving up for.
Holeshot
Banned
I got a 2012 6speed on 35's. I'm actually running the factory 3.73 and it's not so bad on highway and for mudding, but it sucks in rocks. It is a little too fast, I'm always keeping my feet on the clutch when crawling. Would be probably better with the rubi transfer case I guess.
If you're not planning in maybe putting bigger rubbers under, I'd go with 4.56.
But if you're running the 6 speed manual and planning in maybe going bigger someday, I'd go with 4.88.
Here's the chart to help you out.
If you're not planning in maybe putting bigger rubbers under, I'd go with 4.56.
But if you're running the 6 speed manual and planning in maybe going bigger someday, I'd go with 4.88.
Here's the chart to help you out.
Rharvey160
New member
I have a 2012 with 35s, auto with 4.10 gears and find that it does fine here in most parts of Texas. In September I was in the Ouray-Silverton area and the combination really sucked up there. Not on the trails but on the roads in that area. On steep inclines the RPM would jump up real high and the transmission would not change to the next gear. You would have to let off the gas to get the RPM back down. Try to go any faster and the process starts over again. This was mostly on the Million Dollar road between Durango and Ouray. Other places it was not as bad.
In some ares of the Moab area I had the same results but not near as bad.
I wonder if 4.56 gears would help with that? Per the computer I get an average of 14.5 to 15.5 MPG. Gas was $3.11 this morning when I filled up so that was a real treat!
Thanks for that reply I was wondering the exact same thing. I have an 11 Rubicon with 35's and didn't know what gears to go with.
Let me ask you, if I decide later to go to 37's, what gear ratio would you recommend. I don't want to have to do it twice and want to make sure I get this right. I am torn between staying with 35's and going to 37's, the main thing holding me back.... will I pass Mass inspection!
Thanks
JKAnimal
Caught the Bug
I was in the Gunnison and Crested Butte area in Sept. I really didn't have any problems on the roads but I have a manual so I was able to make the decision when to shift instead of letting the Jeep computer decide. Still got about the same gas mph.
White_JKU
New member
I have a 2012 Auto with 3.21's and 35" tires.....
I feel no desperate need for a re-gear..... drives everywhere in GA just fine. I avg. 14 MPG during my normal life.
When I go on long road trips..... I get about 16-17 MPG.... (but thats rare)
I personally think that if I had 4.10's or 4.56's- I would fare a little better in the MPG range.... But 1-2 MPG difference is going to be very hard to see in your wallet.:werdsign:
gtony12
Caught the Bug
Thank you! I have been going back and forth on it, do you find that your overdrive kicks in and out all the time? I really want 35's, and I plan on re-gearing later just need to do all mod's in sections.
Crane guy
New member
I have a 2012 JK unlimited Rubicon with 31" BFG, auto with 3.73 and was getting 17 mpg in the city, and pretty happy with the performance. Now I'm running a 6" teraflex long arm with 38"x13.5x18" my performance is almost like stock but my mileage is around 14-16 mpg. I lost a little in the MPG department, but that's probably due to more mass in the tires and wheel, plus adding the weight of after market front & rear bumpers & a 9.5 warn winch? Over all I love it! ;-) I would like any feed back on my 4.88 choice in gears. I was leaning towards economy, since its my DD
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jkaddict
New member
Sweet Jeep. What part of OR do you live in? I can only speak from personal experience, but I'd say that 4.88's would be a good choice for running with 38's. Running 4.56's with 35's (actually closer to 34's) pushed my rpm's up a little higher than I expected (about 2650@70mph), and it hurt my gas mileage. If I drive 55 on the freeway I can still average high 18's..but who wants to drive 55?? lol Driving 70 gets me into the 15's. Here's a link to a calculator that you may find useful..http://www.race-cars.net/calculators/rpm_calculator.html OD ratio in the auto is 0.83, and 6th gear in the manual is 0.797 Hope that helps..
familytime2
New member
We have an 2007 jk,auto,4.88 gears sitting on 35's,6" lift on avg.we get high 18-19 mpg's based on 60mph highway.As always the faster you go the more fuel used.With this setup i can still upgrade to 36-37 tire size without losing performance
Trail_Creeper
New member
What kind of RPMs are you running down the highway (65-70mph)