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

[syreeves]

I wonder how many have paid close attention to the modern design of semi tractors. The cab these days makes sure the fronts and sides of the tires are not exposed to the wind of travel any more than necessary. Some of those cabs cover 4/5 of the front of the tire. I've passed a couple that actually had flat plates on the wheels to cover the wheel dish on the rear wheels and on the trailer wheels. Those deep dishes catch wind. And we've all for many years seen those ground effects that direct wind away from the rear wheels on the trailers.
Even the dish of our wheels matters - so a deeper dish wheel is more drag. Frontage of the tire exposed is drag and the more aggressive the tread, the more drag.
The tire's foot print being larger - front to back (diameter) and side to side (width of the tire) matters as does tread design.
Lift it and more air gets tangled up in the fender wells and under the vehicle. Modern vehicles looking for MPG have a smooth undercarriage. When I have to clean bugs off my suspension and steering - I know I'm catching a lot of wind with the suspension and steering.
The normal wind speed on a day with any wind is higher off the ground than at ground level - so you raise the truck into higher wind speeds as well as catching air and causing drag under the vehicle.

I agree. Most JT's mine included are pretty much tricked out to REDUCE aerodynamic efficiancy. But they look good. And a little warming up here in MN isn't all bad...

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[WAOverlandJT]

I’ll add a data point.

-Rubicon
-35’s
-mopar lift
-Rebel Off-road half-rack
-steel bumper

I’m getting about 15.1. Thinking about taking off the wings of the bumper for a while to run it as a stubby just to see how that impacts my mpg’s.

I would be really curious to see the impact

 

[Tim]

Over 11,063 miles i have averaged 14.8mpg.

Now this is real data. I think it's starting to come out a little bit in this thread but claims of 20+ mpg are limited portions of driving and not representative of of real average MPG. As @Jeeperjamie mentioned, any of us could claim outrageous MPGs but in the real world there is stopping, accelerating, passing, traffic, etc. We don't just drive 55mph.

 

[MMMII]

I would be really curious to see the impact

After 2 tanks of gas I was at 14.5 in stubby mode Vs. 15.1 in full bumper mode.

Not scientific but I added the wings back on.

 

[ShadowsPapa]

Now this is real data. I think it's starting to come out a little bit in this thread but claims of 20+ mpg are limited portions of driving and not representative of of real average MPG. As @Jeeperjamie mentioned, any of us could claim outrageous MPGs but in the real world there is stopping, accelerating, passing, traffic, etc. We don't just drive 55mph.

Mine are real long-term numbers. That includes trips to Colorado and back, Indiana and back as well as other trips (with my wife driving 75-80 mph at times) and me driving faster than that twice trying to outrun massive storms (meaning I've had mine upper 80s as far as speed.

Before my added weight and tire change, it was routinely over 20 - at times 22-23 and that's verified not just "the cluster says". I keep receipts and use a phone app. A total mix of driving, interstate, rural roads, shopping in town, stop and go, I still do 19 and that's with the colder weather set in. When it's warm it will go back up 19-20. If I took the steel bumper and winch off and went back to stock tires I would absolutely be getting 22-23.

Amazing how when others get different results, then those getting the higher numbers are liars.

I'm not claiming anything - just laying out the facts as they are. I set my odometer to be spot-on by using a GPS and phone app, I don't under-inflate my tires like some people seem to think is more manly or for some reason better. I run them as the tire company support engineer suggested most of the time.
I towed 5,000 pounds at 65 mph through the hills of eastern Iowa where even the big rigs have to keep shifting to maintain speed and got a verified 13.9 mpg. In other words, I got more towing my car hauler loaded with car than my Silverado got towing the same thing.
I've posted the charts and images from FillUp the phone app.
You can't go by a single tank because when you park and fill there's no way you are getting exactly the same amount of gas back in that you pulled out - so one has to account for the highs and lows.

In short, my numbers are no claims, they are fact. I check the numbers, my odometer is accurate - unlike most people here do "speedometer matches up so it's good". No, it's not necessarily. Odometer is the only real way to be 100% accurate.

If people run their tires where they should run them, set the tire size in the BCM based on the ODOMETER and not the speedometer and stop using "I was told to use this number" but do it right, and realize that any changes from stock will almost certainly impact mpg in a negative way, then maybe we'd be somewhere?

 

[NC_Overland]

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

I’m pretty sure it makes a difference on the Gladiators if you do run it in auto 4wd (I know you aren’t). I had that option in my 2017 Canyon, which was also a 3.6l/8 speed auto and it dropped the MPG significantly. My Overland is a 2020, so it wasn’t available as an option. Just throwing that out there…

 

[texanjeeper]

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.

Yep. This. It's the smartest answer I've seen so far. The weight of the tires is likely dramatically higher than the ones you replaced, I'm betting.

 

[Jeeperjamie]

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.

I'm at 98lbs a corner roughly and I'm able to get just above 17 most of the time. I have dropped to around 16.7 for a few days since it's gotten down to below 30 a few days and no higher than 50 but as soon as it got back to getting in the 60's I was able to get it back up to 17.2. All my data is long term, I got over 40,000 miles on mine. 18,000 miles of those on 315 70 17 BFG KO2S where I never saw below 18.2 Mpgs and could get as high as right at 20 on a long trip. I've been running 37's for the last 22,000 miles and it dropped to 17.2 for the most part and i can get around 18.2 on long trips. Stock gearing 4.10 gears sitting like this

 

[Deleted member 30519]

I'm getting 17 mpg with 38" Patagonias. I wonder how much I'd get if I diddnt have rear steel bumper, front steel bumper, bed rack , steel side steps and winch. Maybe 19

 

[NC_Overland]

Just my 285/70/18s wheel tire combo is over 80 lbs a corner.

 

[Tim]

Mine are real long-term numbers. That includes trips to Colorado and back, Indiana and back as well as other trips (with my wife driving 75-80 mph at times) and me driving faster than that twice trying to outrun massive storms (meaning I've had mine upper 80s as far as speed.

Before my added weight and tire change, it was routinely over 20 - at times 22-23 and that's verified not just "the cluster says". I keep receipts and use a phone app. A total mix of driving, interstate, rural roads, shopping in town, stop and go, I still do 19 and that's with the colder weather set in. When it's warm it will go back up 19-20. If I took the steel bumper and winch off and went back to stock tires I would absolutely be getting 22-23.

Amazing how when others get different results, then those getting the higher numbers are liars.

I'm not claiming anything - just laying out the facts as they are. I set my odometer to be spot-on by using a GPS and phone app, I don't under-inflate my tires like some people seem to think is more manly or for some reason better. I run them as the tire company support engineer suggested most of the time.
I towed 5,000 pounds at 65 mph through the hills of eastern Iowa where even the big rigs have to keep shifting to maintain speed and got a verified 13.9 mpg. In other words, I got more towing my car hauler loaded with car than my Silverado got towing the same thing.
I've posted the charts and images from FillUp the phone app.
You can't go by a single tank because when you park and fill there's no way you are getting exactly the same amount of gas back in that you pulled out - so one has to account for the highs and lows.

In short, my numbers are no claims, they are fact. I check the numbers, my odometer is accurate - unlike most people here do "speedometer matches up so it's good". No, it's not necessarily. Odometer is the only real way to be 100% accurate.

If people run their tires where they should run them, set the tire size in the BCM based on the ODOMETER and not the speedometer and stop using "I was told to use this number" but do it right, and realize that any changes from stock will almost certainly impact mpg in a negative way, then maybe we'd be somewhere?

Thanks for the reply but aren’t you running 33‘s? My comments regarding the accuracy (or lack thereof) of MPG claims were in no way directed in your direction.

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