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Huge MPG change?

Yallaen

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My ride is a 2020 Gladiator Sport-S. Had 18" rims with 32" Bridgestone Duelers. I got about 18-19 MPG around town.

I added a lift kit, which should not affect anything mileage wise I would think. I got a new steel bumper. When I got the lift kit, I went to 35x12.5 Toyo's. I'm noticing my MPG is down to 15 MPG. That's about a 20% loss. Is this normal/expected?
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USMC-SSGT

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You are almost in my same setup. Yes, that’s 100% normal and expected.

A lift kit picks the truck up and exposes more to the wind. Wheel wells and undercarriage etc

Bumper, while the steel version is still a hit aerodynamic wise and for the small weight increase.

Wheels are the killer. Rotational mass coupled by a lot more surface area and an AT/MT tread compared to factory.

Long story short- 15-16 mpg is your new home.
 

Hipbilly

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It only gets worse.

Jeep Gladiator Huge MPG change? altering-the-deal[1]
 

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BAT

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You are almost in my same setup. Yes, that’s 100% normal and expected.

A lift kit picks the truck up and exposes more to the wind. Wheel wells and undercarriage etc

Bumper, while the steel version is still a hit aerodynamic wise and for the small weight increase.

Wheels are the killer. Rotational mass coupled by a lot more surface area and an AT/MT tread compared to factory.

Long story short- 15-16 mpg is your new home.
Yep
 

jay21mojave

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Run that on the MOJAVE .w/35/11.50s and you'll Look at 14 in town and 17 Hwy (70mph cruise).
 

ShadowsPapa

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My ride is a 2020 Gladiator Sport-S. Had 18" rims with 32" Bridgestone Duelers. I got about 18-19 MPG around town.

I added a lift kit, which should not affect anything mileage wise I would think. I got a new steel bumper. When I got the lift kit, I went to 35x12.5 Toyo's. I'm noticing my MPG is down to 15 MPG. That's about a 20% loss. Is this normal/expected?
Yup - you raised the main sail with the lift.
Yup - you exposed more front tire to the wind. That's why vehicles today try to block off the oncoming wind from the fronts of the tires.
And yes, heavier bigger tires will do it, as well as steel bumper (I know first-hand the steel bumper and skid plate make a difference, also saw a difference going from the stock H/T duelers to A/T type tires a bit wider)
Tires with more aggressive and/or wider tread mean more rolling resistance (not to mention likely weight gain). Any tire dealer worth a crap will tell you that.

I think you are about right.
I dropped a good 4 or so mpg with my own changes.
 

Jeeperjamie

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If you got 3.73 gears then that's expected. I got 4.10 gears on my Sport Max Tow and I get around 17.2 to 17.5 on 37 12.5 17. You also picked one of the heavier 35's, yours weigh more than my 37's do and if you went with a stubby bumper or any bumper that doesn't close in the gap between the fenders and the bumper then air is getting up inside those fenders when you ride and that's causing wind resistance. The higher you go up in lift then the worse it's going to get, plus the added weight of the bumper didn't help either.

That's why I chose a full width bumper with high clearance ends to close back that gap between the fenders and the bumper, plus I took weight of the tires, bumper and winch into account as well, even down to the types of lights I decided to mount. Believe it or not every little detail matters when it comes to aerodynamics, even lights. Lights bars block air flow and push air up instead of around the jeep, especially light bars put above the windshield. Just saying and giving a few tips, I'm sure someone will try to contradict what I'm saying but after building a few of them you get an idea of the do's and don'ts. Mine as it sits to give you a idea of what I'm talking about. I have never had a problem pretty much staying above 17 Mpgs and on occasion above 18 on longer trips. A few days I've been at 16.7 and those were colder days when it was below 32° in the morning and no higher than the 40's in the evening.



PXL_20211111_121139651.jpg


PXL_20211111_121139651~2.jpg


Would love to see your setup for comparison
 

NC_Overland

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My ride is a 2020 Gladiator Sport-S. Had 18" rims with 32" Bridgestone Duelers. I got about 18-19 MPG around town.

I added a lift kit, which should not affect anything mileage wise I would think. I got a new steel bumper. When I got the lift kit, I went to 35x12.5 Toyo's. I'm noticing my MPG is down to 15 MPG. That's about a 20% loss. Is this normal/expected?
Yes. Need to re-gear and you’ll get a few mpg and a lot of power back.
 

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NC_Overland

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If you got 3.73 gears then that's expected. I got 4.10 gears on my Sport Max Tow and I get around 17.2 to 17.5 on 37 12.5 17. You also picked one of the heavier 35's, yours weigh more than my 37's do and if you went with a stubby bumper or any bumper that doesn't close in the gap between the fenders and the bumper then air is getting up inside those fenders when you ride and that's causing wind resistance. The higher you go up in lift then the worse it's going to get, plus the added weight of the bumper didn't help either.

That's why I chose a full width bumper with high clearance ends to close back that gap between the fenders and the bumper, plus I took weight of the tires, bumper and winch into account as well, even down to the types of lights I decided to mount. Believe it or not every little detail matters when it comes to aerodynamics, even lights. Lights bars block air flow and push air up instead of around the jeep, especially light bars put above the windshield. Just saying and giving a few tips, I'm sure someone will try to contradict what I'm saying but after building a few of them you get an idea of the do's and don'ts. Mine as it sits to give you a idea of what I'm talking about. I have never had a problem pretty much staying above 17 Mpgs and on occasion above 18 on longer trips. A few days I've been at 16.7 and those were colder days when it was below 32° in the morning and no higher than the 40's in the evening.



Jeep Gladiator Huge MPG change? PXL_20211111_121139651~2


Jeep Gladiator Huge MPG change? PXL_20211111_121139651~2


Would love to see your setup for comparison
I took tire weight into consideration and that’s also why I only went from 255 to 285 on my stock overland 18” wheels and gearing. My research paid off and my MPG is roughly the same. Which is surprising since I have lost 8th gear on anything but flat ground. I also still have stock bumpers and stock (rubicon) suspension.
 

ShadowsPapa

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Yes. Need to re-gear and you’ll get a few mpg and a lot of power back.
Sport S - do we know if it's max tow or not - 3.73 or 4.10 gearing?
I'd think 4.10s would be fine with 35" tires.
However - you made me think to ask -

When the tires were changed HOW was the speedometer/odometer recalibrated? Is it accurate or was a number plugged in that someone gave him and it was called good enough?
 

redrider

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The 4.0 I6 in the yj got 17 all day long with a 2 inch lift and 33s. The Cherokee gets a touch better with the auto and wifey in the pilot seat. The Pentastar is better?
 

Daddiator54

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Freedom edition here (sport s w/ steel bumpers) and max tow. I threw on new wheels and 35’s along with a lvl kit in the front. Adjusted the realistic tire size in the computer with a tazer. Currently get an average of 15mpg city and 17.5 highway (70mph tops) no other mods and hauling nothing but my wife and kid. Gas guzzler for sure. I live in Florida so it’s as flat as you can get and I feel like I drive like a grandma.

Funny because I see some of these pictures of ppl with their dash at like 22mpg+ who swear they run 35’s and are not diesel. I don’t doubt the pic but somethings got to give because I know my setup and I don’t get near that.
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