loss of gas mileage

wayoflife

Administrator
Staff member
yes jeep had to do it.. but it is recalibrated it for sure

Well, I have no experience with 37's on a turbo but that could be a part of what you're seeing. For sure you will see MPG loss with bigger tires but 7 seems a bit much if you're comparing apples to apples conditions like driving for an extended period of time at 55 MPH. Of course, more than size, the new tires you're running will have a LOT more rolling resistance than factory all terrains and they will for sure eat up MPG. If you had a set of 37" street tires, I can guarantee you that you'll see an increase in MPG.
 

Poppasim

New member
ahh ok... i just tested the speedometer against waze app, before they were similar now its about 8 to 10 miles off.... I might need to recalibrate it again... its a 2019 so supposedly after markets won't read it, only the dealer can do it.. Supposedly

Sent from my SM-G965U using JL Wrangler Jeep Forum mobile app
 

wayoflife

Administrator
Staff member
I Agree^^^ maybe also check your air pressures for on road. Did you go with a larger wheel also? Maybe weight is playing a bit into it?

Tire pressure will make a difference for sure as well but weight of the tires really won't effect MPG.

i never tried the Tazer, my custom shop only tried the AEV and it didn't work.. so I guess based on that I was told that the 2019's can only be calibrated by the dealer...I need answers.. lol

AEV will only work on JK's. You need a Tazer or have your dealership do it.
 

JrBiem

New member
It's not so much a problem, just has more rolling resistance. I've tested out a 37" Falken Wildpeak AT against a 37" Toyo MT in the past, just to see how rolling resistance would affect MPG and saw a 4 MPG difference.

What kind of mpg are you getting on the 37" stt pros and what pressure are you running? I've got 315 trail grapplers @ ~28 psi and I'm only getting about 13.5 mpg. It's a sport with 3.45's, do I need to re-gear? Speedo is corrected w/ Tazer.
 

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Wranglerman

New member
I put 315 KO2’s on my 3.6 2018 JLU Sahara and calibrated with a Tazer and speedo is spot on from 75 mph and down and lost about 2-3 mpg, was running 32-34 psi but after chalk testing ended up at 29-30 for good contact.

Had better mileage with higher pressure but was riding on the crown so just kept lowering until I got even contact all the way across but also lost some mpg’s but that’s ok it’s a Jeep not a Prius
 

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