13.1mpg best I can get with 35’s. Questions inside…..

[WAOverlandJT]

It’s been just over 4k miles so far and mpg just seems to keep dropping. I even baby the S out this thing when driving it. I have a rack and roof top tent so I figured that’s killing it the most. I took it off about a week ago and still getting 13.1 with city/hwy mix. Everyone on this board is posting like 15-20 and many have more mods and bigger tires. So trying to figure out wtf I can do to get more range out of this thing.

I’m wondering if maybe the tazer could be causing an issue somehow. Going to take that off and test this week.

21 rubicon
35” Baja atz with 17” fuel zephyr wheels (kinda heavy wheels).
RR arcus stubby bumper
Taser mini- updated about 2 months ago to fix issues it had.
4h auto ( I wonder if this also drops mpg
I run regular fuel, so 87/89 normally.

Thoughts on stuff to try? I read the thread with the pulsar but that won’t work on the 21 I guess.

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[DocMike]

I see about 14-15. I have lots of hills out here. And altitude kills things.
I'm on 35s with a 2.5 in lift. 4.88 gearing.
When I get on the highway it is much better, but around town for short trips it drops to 13.
Are you relying just on the computer? Or are you calculating mileage old school? I know I have to reset my mileage in the computer. Even then it's quite suspect.

 

[Lateralus]

I get 17 right now city with 35's, sidesteps, and an aluminum bed cap. You've got considerably more added weight it appears, than I do. I know it's always nice to get better fuel efficiency but I think when you start adding stuff, especially bigger tires, you need to be realistic.

 

[WAOverlandJT]

I get 17 right now city with 35's, sidesteps, and an aluminum bed cap. You've got considerably more added weight it appears, than I do. I know it's always nice to get better fuel efficiency but I think when you start adding stuff, especially bigger tires, you need to be realistic.

The 13.1 mpg is no tent on and no gear in. So about 4mpg less than you and guessing weight is pretty close with your mods. That’s why it feels like something is off for me.

 

[Lateralus]

The 13.1 mpg is no tent on and no gear in. So about 4mpg less than you and guessing weight is pretty close with your mods. That’s why it feels like something is off for me.

Yea that seems low then.

 

[WAOverlandJT]

I see about 14-15. I have lots of hills out here. And altitude kills things.
I'm on 35s with a 2.5 in lift. 4.88 gearing.
When I get on the highway it is much better, but around town for short trips it drops to 13.
Are you relying just on the computer? Or are you calculating mileage old school? I know I have to reset my mileage in the computer. Even then it's quite suspect.

Just going off using the trip computer since I had the tires adjusted with the taser. I will try manually calculating but based on my range I get it seems like it should be right.

 

[DocMike]

I know many on here have suggested that you need to flog the pentastar a bit.
Drive it a bit harder. I do have a lot of weight. Sliders, steel bumpers, winch, black rhino rims, skids, lift, fat old rugby player.

Just going off using the trip computer since I had the tires adjusted with the taser. I will try manually calculating but based on my range I get it seems like it should be right.

 

[thiccar]

4h auto ( I wonder if this also drops mpg
I run regular fuel, so 87/89 normally.

Dumb question, does this mean you are driving around in 4WD?

 

[MrFahrenheit]

Dumb question, does this mean you are driving around in 4WD?

Jeep has a T-Case that was an option for the JT (21 MY I believe) that has 2HI, 4 Auto (think AWD of sorts), 4 HI, and 4 LO

 

[johnparjr]

I get 13-14 city and 16-18 highway on 35’s MT gonna switch to AT after these wear out and see if that helps. Might also go back to 33’s

 

[WK2JT]

I would suggest not driving in 4H Auto unless you are in mixed conditions, rain, sleet, snow, etc. However, I do not believe that would affect your mileage that much, it just engages the FAD so the transfer case can automatically go from 2H to 4H. By having the FAD engaged it will introduce some minimal additional drag. Are you still on stock 4:10 gears or did you change gears? I ask because are you sure you have your wheel size and gear ratio set correctly in the Tazer? These values can throw off the computer calculation if not set correctly. That would be the easiest check first. I have 37’s with 5.13’s and the lowest I see around town is about 15 mpg.

 

[WAOverlandJT]

Dumb question, does this mean you are driving around in 4WD?

No, it just is equipped with 4h auto. I had read that in other Jeep models they had issues with those. So I figured I would mention if others have crap mpg and that option

 

[staying_tuned]

Sounds about right given the additional weight. The wheels you’re running are very heavy and 35” wheels vary drastically in weight. The baja atz in 35x12.5 is 70lbs.

At >100lbs. per corner, yeah, not going to get much better than low teens.

 

[ShadowsPapa]

No, it just is equipped with 4h auto. I had read that in other Jeep models they had issues with those. So I figured I would mention if others have crap mpg and that option

Dunno what you've been hearing - but no, no issues. And if you don't have it in 4H auto, it has no impact on anything, it's like any other t-case in 2 wheel mode.
Heavy tires and heavy wheels matter - I know what others will say "I have 35s and am fine" - I have to laugh a bit because a 35 can vary almost a full inch in diameter and many pounds in weight. So unless someone says they have the exact same brand and size tires in the same load range - you can't really compare.
These are also very picky on weight and the frontage presented to wind.
I noticed a difference when swapping bumpers. If air hits the fronts of the front tires, it's more wind resistance. The plastic bumpers prevent that, and the sport that has the extra piece between bumper and front edge of fender prevents that even more.
I used to get 23 and more very easily. Now I'm about 20-21 most of the time.
I changed to A/T tires a tad wider, added a steel bumper, etc. - and lost a good 2 to 3 mpg with my changes.

 

[WAOverlandJT]

I would suggest not driving in 4H Auto unless you are in mixed conditions, rain, sleet, snow, etc. However, I do not believe that would affect your mileage that much, it just engages the FAD so the transfer case can automatically go from 2H to 4H. By having the FAD engaged it will introduce some minimal additional drag. Are you still on stock 4:10 gears or did you change gears? I ask because are you sure you have your wheel size and gear ratio set correctly in the Tazer? These values can throw off the computer calculation if not set correctly. That would be the easiest check first. I have 37’s with 5.13’s and the lowest I see around town is about 15 mpg.

Yeah I don’t drive in 4h auto, just mentioned it as an option incase that could be part of the lower mpg.

Still on stock 4:10 and checked to make sure the tazer shows that yesterday. Correct tire height is showing also. This tazer has had some issues in the past where I needed to reset it multiple times to clear the problems. So that’s my gut. I didn’t want to swap to 5.13’s until I run these tires down and swap to 37’s.

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