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35" and 37" effect on MPG

StewDog10

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I just bought a 2018 JL with 37s (Nitto Trail Grapplers). It hs Active Desert Design Rock Fighter Front and Rear Fenders which act as a sail and hold the thing back massively. Regardless, on the return trip picking it up I got exactly 12.3 mpg. On the highway . . .
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blnewt

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I just bought a 2018 JL with 37s (Nitto Trail Grapplers). It hs Active Desert Design Rock Fighter Front and Rear Fenders which act as a sail and hold the thing back massively. Regardless, on the return trip picking it up I got exactly 12.3 mpg. On the highway . . .
The whole Jeep is a sail, just gotta go with the wind :)
 

Azrael5988

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I have a 2020 Eco diesel Sport. Was getting Damn near 30mpg with stock tires and suspension. With 2 inch factory lift and 35” KO2s I’m getting between 18 and 20 mpg, depending on my foot. Granted these are short trips. Haven’t made a road trip with the new setup yet.
 

Zandcwhite

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In the same type of daily driving, we went from 18-19 to 15-16 going from stock to 2.5" lift and 37" geolander x-mt's. On long roadtrips with the cruise control set at 85mph, more like 14.
 

4xFUN

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My average MPG over 10,000+ miles is 15.6 and all of that (except for less than 100 miles on stock tires) are on 35's and most of that (except about 1500 miles) were with a Mopar lift. I also have Warn bumpers, Warn winch, skids, heavy aftermarket steering (tie rod, drag link and trackbar's) plus a heavy foot. I have zero complaints!

Soon will be going with 37" KO2's but also switching to 4.88's, will be interesting to see how this affects mileage.
 
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jabtyler

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I am running Nitto ridge grapplers 37 13.50 with a Mopar lift and RK spring straighteners so closer to 2.75+ lift. I am getting 17mpg mostly city driving. its the 2.0 auto. I have bumpers skids and a winch too. so kinda heavy.
 

zouch

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did you re-gear? if yes, to what ratio?

how did you adjust your speedo/odo to compensate for the larger tire size?


I have a 2020 Eco diesel Sport. Was getting Damn near 30mpg with stock tires and suspension. With 2 inch factory lift and 35” KO2s I’m getting between 18 and 20 mpg, depending on my foot. Granted these are short trips. Haven’t made a road trip with the new setup yet.
 

Azrael5988

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did you re-gear? if yes, to what ratio?

how did you adjust your speedo/odo to compensate for the larger tire size?
Didn’t regear, when the dealership installed the bigger tires and lift ( part of buying my rig) they did it. But honestly you can buy a tuner that will do that plus much more.
 

Kurt0

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3.6; 8spd; 37’s; 4.10’s. Hand calc was 22.5 iirc.

Jeep Wrangler JL 35" and 37" effect on MPG A7FDA417-CC6A-4B56-A176-2BB5F9A0E622
 

Warped

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For those running 35s and 37s, have you calculated the MPGs before and after?

The big loss of mpg for me wasn't with the tires going from 33 to 35". That barely made a dent in my mpg from stock. But, adding the lift, winch, bumpers, and all the other weight; fuel economy dropped fairly significantly.
 
 



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