Can Believe my gas mileage

[Shots]

I doubt you'll have a huge drop in fuel efficiency. It will go down a bit due to added weight, but that's true of adding any tire that is larger than stock (it won't matter if they're Rubi take off or aftermarket).
Having come from a Ram that got roughly 12 mpg, I'm thrilled with 20+ mpg. One thing you'll notice when swapping to a bigger tire is that they calculated efficiency will decrease, but one thing people forget when they hand calculate is to adjust for the increased circumference of the tire. It's not much, but a larger diameter tire will log less miles. As a result, when you calculate efficiency it shows less efficient than it is because you didn't account for all the miles driven. This is the same issue with the computer's reported efficiency after a tire swap for the same reason. It really is a minor difference, but if you lose 1 mpg, and forget to calculate some miles, that results in .5 mph difference, it makes the loss look worse than it was.

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[Jeepsterfreak]

I doubt you'll have a huge drop in fuel efficiency. It will go down a bit due to added weight, but that's true of adding any tire that is larger than stock (it won't matter if they're Rubi take off or aftermarket).
Having come from a Ram that got roughly 12 mpg, I'm thrilled with 20+ mpg. One thing you'll notice when swapping to a bigger tire is that they calculated efficiency will decrease, but one thing people forget when they hand calculate is to adjust for the increased circumference of the tire. It's not much, but a larger diameter tire will log less miles. As a result, when you calculate efficiency it shows less efficient than it is because you didn't account for all the miles driven. This is the same issue with the computer's reported efficiency after a tire swap for the same reason. It really is a minor difference, but if you lose 1 mpg, and forget to calculate some miles, that results in .5 mph difference, it makes the loss look worse than it was.

Wait. Are you saying the odometer reading is off unless you recalibrate the computer for larger tires? I guess that makes sense since it throws the speedometer off also.

 

[Richamby]

Yes the miles go on slower. You travel 100 miles but it registers 95.

 

[WXman]

The Rubicon take-offs are 0.25" taller and roughly 10 lbs. heavier. Not a huge difference. You'll see a 1 MPG decrease.

If you go with 34s or 35s, that's when you start seeing the 2-4 MPG bombs that others have been talking about.

 

[Richamby]

Thanks for the info, I’m stoked about my gas mileage and don’t need 35’s or 37’s.
It’s taken Jeep a long time to get a Wrangler or Cherokee over 22 mpg in the real world.

 

[GRAK]

You must have a heavy foot. I get around 20 in Phoenix.

Yeah I don't get it. About to head out camping in SoCal so will be watching it with these new 315 Cooper STTs

 

[Chinarider]

Jeez...I'm only averaging 14.1 mpg so far! This is with a JLUR, 6-speed m/t, and only 500 miles of very conservative, gentle break-in miles on her. Two factors that I'm sure have a lot to do with this: 1) this is mostly driving around town - very few freeway miles, and; 2) I live on the coast, near San Francisco, so it's pretty hilly. My street alone peaks at about a 20% grade.

 

[TheWingman]

Jeez...I'm only averaging 14.1 mpg so far! This is with a JLUR, 6-speed m/t, and only 500 miles of very conservative, gentle break-in miles on her. Two factors that I'm sure have a lot to do with this: 1) this is mostly driving around town - very few freeway miles, and; 2) I live on the coast, near San Francisco, so it's pretty hilly. My street alone peaks at about a 20% grade.

I’ve got the same exact wrangler. You’re going to be VERY happy with how the drivetrain breaks in. Mine did the same thing, but right around 2k miles my mpg jumped above 19 without much change. Now sitting at 21.3mpg over the last 4K miles

 

[Shots]

Jeez...I'm only averaging 14.1 mpg so far! This is with a JLUR, 6-speed m/t, and only 500 miles of very conservative, gentle break-in miles on her. Two factors that I'm sure have a lot to do with this: 1) this is mostly driving around town - very few freeway miles, and; 2) I live on the coast, near San Francisco, so it's pretty hilly. My street alone peaks at about a 20% grade.

Wow, I expected you to say it was lifted with bigger tires or something. That seems pretty bad. Not to add insult to injury, but the 20+ I'm getting is with an automatic, with under 700 miles that has yet to see the interstate. Granted my "city" driving is pretty rural by most standards. I think there are somewhere around 10 traffic lights on the main road through town, otherwise it's stop signs and 45-55 mph zones. That and our hills (though plentiful) aren't near as steep as yours. They're usually 10% or less.

 

[Shots]

Wait. Are you saying the odometer reading is off unless you recalibrate the computer for larger tires? I guess that makes sense since it throws the speedometer off also.

Yes, that it is correct. For example a tire that is 33.0" tall will travel 103.62" every revolution (or 611.46 revolutions per mile) . A tire that is 34.0" tall will travel 106.76 every revolution (or 593.48 revolutions per mile). That difference of roughly 18 revolutions per mile, means your Jeep thinks it has traveled 155 feet less than it actually has with every mile you drive.
It is a minor difference, but it adds up. If you drive 100 miles, your Jeep only reads 97 of them. So when you fill you tank and do the math it will throw you off a bit. It's minimal, especially if you only go an 1" or less, but it does affect the calculations. Yes the added weight, and torque required to rotate a larger diameter will have the greatest affect on mpg's, but the un-logged miles often gets missed in the calculation leading people to think they lost more than they did.

To go a step further. Using the above example, the reading is roughly 3% difference in miles logged. Let's say the weight is exactly the same, and the torque required isn't a factor (just to keep the comparison even). If you average 20 mpg, and log 3% loss it would look like you were getting 19.4 mpg. A loss of 0.6 mpg which often gets chalked up to heavier tires. Nope, just a loss of accounted for distance.

 

[Richamby]

20+ mpg in 4 door 4000 pound Jeeps with automatic transmissions is like being in Jeep Heaven.
This V6 engine and 8 speed transmission is a game changer for me.

I no longer feel like I’m taking money out of the family budget when I drive my JL because my wifes car gets about the same.

 

[MartyParty]

Here’s my figures from a Vegas to Phoenix trip a few weeks ago. Seems like the stretch of 93 from the 40 to Wickenburg is fairly downhill, which helps lol.
Oh it’s a Sport Unlimited, 6spd. Stock 245’s. Plenty of shifting which I really didn’t mind, kept things interesting. It’s funny, you bog against anything in 6th, 5th is not much better so you grab 4th and it zips up to 75, back to 5th, hey we’re around 80, 6th, oh here’s a hill.......and repeat. Only in a Jeep lol.

 

[smithrd65]

I'm averaging 21.5 mpg after 5000 miles. I'm good with that.Using cruise Co tool keeping speed at 71 - 75 it's easy but if you stomp the peddle 18 - 19mpg.

 

[guarnibl]

That's some solid mileage. Big tires certainly kill mpg but so do things like a lift, flat fenders, and heavier bumpers. My 98 TJ with a 5.7 hemi got a hair over 16 mpg today from PHX to Payson and back. I was actually pretty surprised... I know power helps in the hills but I feel like that's probably better than a 4.0 would have gotten in the same conditions. That's with a 4" lift, 33's and 4.10's, but no winch and stock bumpers/fenders. Ran AC the entire time with soft top down going about 70.

 

[Bingy]

There is no doubt lifting your jeep adds to the frontal surface area, this combined with bigger heavier tires takes its toll. I wouldn't recommend bigger tires or a lift on a Sahara or sport without re gearing to 4:10 on 35 or higher for 37's. This will impact your mileage also. I'm running 28 psi in my 35 inch k02's with 9 inch rims. I get 16.5 in town. I might see 19 on the freeway.

A Sahara with a 3.6L 8 speed automatic will handle 35's on 3.45's. Many have this set up. 4.10 or 4.56 will be needed for 37's.

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