13.2 mpg with 37s....

[kapk22]

2021 JLUR, hard top. Plastic bumpers. 35” spare.

tires -37x13.50r20 Nitto Mud Grapplers.

Mostly city driving, commute to work.

I expected a decrease from the 37s, but 13.2 is pretty bad.

ive considered an intake and exhaust, maybe a tuner and gears in the future.
Thoughts??

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[Sunshne×Whsky]

Regear

 

[ldstruckn]

regear

 

[limeade]

I'm running 37x12.50R17 Nitto Trail Grapplers and lots of armor on my 2018 (2.0T eTorque and auto tranny) and am getting roughly 16-16.5 mpg. On my stock 2019 (same engine/tranny), I average 20.5-21 mpg. I saw the biggest mpg hit when I went from 37" Patagonia's to the Trail Grapplers (a lot heavier).

While I had the Pats, I wasn't too concerned with re-gearing. Now it's next on the list, probably going with 5.13's.

Any bolt on engine mod (CAI, exhaust, etc) won't do much if anything to get your MPG's back. Re-gearing is the best and most effective solution.

 

[ML7]

gears and a tuner to change the tire size and gears, and you will notice the power bands again with 37s - get the Mopar cold air intake and an exhaust and you will notice a difference.

 

[runningshoes]

There's something else going on - I'm running 37's, 3 1/2" lift, metal bumpers + winch, skid plates on the V6 and getting 16. You should be getting at least the same. I think there's a thread somewhere showing everyone's MPG if you can find it.

 

[limeade]

gears and a tuner to change the tire size and gears, and you will notice the power bands again with 37s - get the Mopar cold air intake and an exhaust and you will notice a difference.

Good point......@kapk22 have you reprogrammed for your current tire size with something like a Tazer? If not, this could be a part of your poor mpg.

 

[kapk22]

Yes. Forgot to mention I changed the size with the tazer mini.

 

[Chrisdupe]

Tread pattern will make a big difference. Nitto Mud Grapplers have a pretty aggressive tread pattern.

 

[kapk22]

Tread pattern will make a big difference. Nitto Mud Grapplers have a pretty aggressive tread pattern.

I knew they would be a little worse than others. Just didn’t think it would go that far down.

I don’t trust any local shops to touch my Jeep anymore either. So, I will probably have to do the gears myself. Sounds like, maybe sooner than later.

 

[Elsinore73]

I’m running BFG AT KO2’s, 315/70/17 on a stock JLUR, had the dealer reprogram for 35’s and am getting 15mpg around town. I would expect 37’s to deteriorate mileage from there if that helps. Getting about 20mpg straight highway driving.

 

[kapk22]

I’m running BFG AT KO2’s, 315/70/17 on a stock JLUR, had the dealer reprogram for 35’s and am getting 15mpg around town. I would expect 37’s to deteriorate mileage from there if that helps. Getting about 20mpg straight highway driving.

well, then that’s about right. Gears appear to cost about $800. Just have to see what the install process is and save

 

[Bruce Willys]

There's something else going on - I'm running 37's, 3 1/2" lift, metal bumpers + winch, skid plates on the V6 and getting 16. You should be getting at least the same. I think there's a thread somewhere showing everyone's MPG if you can find it.

OP is in Oregon, you’re in the Midwest. There’s a ton of hills in our region, you’re either going up or downhill at most times and the downhill sections do not make up for the wasted energy/gas used going up the hills. I average 17.5 mpg in my stock 2 dr Willys, and I don’t race around or do much city stop and go. With my driving style, I’d easily be getting over 20 mpg if I lived in a flatter, more level state/region.

Edit: Just noticed this is posted in the 2.0T section, my mileage is with a V6 2 dr.

 

[SSWIM]

You will not get your MPG back by changing gears. A little, sure, but never will it be the same. Rolling mass\inertia is there to stay with larger tires. I am sure you probably know this though.

I get 14ish with 37" tires, mixed driving.

Sam

 

[Pappy06]

Yeah, that tire weighs 88 pounds. Gotta regear if you’re keeping them. Rotational weight has the most effect on a vehicle.
Also manually check your MPG just to keep everything empirical.

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