Would a tune or gear change help bad MPG with 35 inch tires?

[InvertedLogic]

No, I bought it this way off the lot. It has not been programmed. It was brand new - dealer added the 35's and lift.

Tire size programming is easy, cheap, and should yield a better driving experience. Auto I assume?

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[jcgoat]

Tire size programming is easy, cheap, and should yield a better driving experience. Auto I assume?

Yes, auto. Is there a tuner that you recommend?

 

[InvertedLogic]

Yes, auto. Is there a tuner that you recommend?

TazerJL is the popular one around here as its multi-use. AEV Snap would do it but only does tire size as far as I know. Might be able to do it with the JScan app and a programming cable as well.

I used a Tazer Mini that I had from my JL. Big difference in drive feel, shift points, and mpg on my Rubi when I went to 35s.

These trucks use Torque On-Demand, and need to know how big the tires are in order to accurately deliver the torque request you ask for when you press the pedal. Otherwise, it thinks you're towing since you're not following the expected acceleration target.

 

[iadslgladiator]

I had a gasser with 37's, manual trans and 3.73 gears. While 37's aren't really comparable to 35's, I cant imagine that you wouldn't need to regear to retain any semblance of factory performance and mpg's. There is no benefit to a tuner without doing lots of other performance mods and getting a custom tune..
Even with the tiny factory wheel/tire package I wasn't getting over 20, highway or town, best I was ever able to do with the 37's was just shy of 17 but that was straight highway 65ish basically flat grade or downhill with a tail wind! Anything marginally up hill, a head wind or speeds of 70 plus (read:normal conditions) and I was lucky to get 13.

All that said, you could try one of those throttle manipulators. It isnt gonna change any actual power numbers but could change the "seat of the pants feel" as it eliminates the lag in throttle response.

 

[hjdca]

I have 35's on my Gladiator Overland and the gas mileage is crap. Would a tune or gear change help?

yes, a gear change will help a lot. The motor is already tuned to get as much mileage as possible. For 35s, You are also running some extra weight on each corner because of the 20" rims. 39 lbs rim with an approx. 63 pound tire puts you over 100 lbs a corner. For example, If you do careful tire and wheel selection, you can run the same weight with 37s and 17 inch rims. Not really a big deal, and you have a great looking setup, but, that will effect your mpg.

 

[HorneyBadger]

Put 35's on my Overland and ran them on the 3.73 gears. Going uphill was painful as it stayed at 4k rpm to maintain. After the trip I called Rebel Offroad for gear change. Now 4.56 gears and much better performer. 4.10's are the minimum with 35's.

and if the dealer put 35's then they should have already changed the programming for tire size. Go back to the dealer and find out so you dont waste your money on a Tazer (Although there are many other niceties in the Tazer and you will need one if you change gears).

My gear change cost $1700 OTD. Expect to pay $500-800 per axle (depending on the gears) plus labor.

 

[DaddyG]

I don’t think it’s the word that’s offensive. I think it’s the fact that people buy a Jeep Truck and put bigger, heavier tires and add more weight via bumpers, etc and expect to get good mileage. Lol. I’ve always heard the same argument with trucks. I have never bought a truck and expected good gas mileage. I buy trucks for a purpose. The fuel mileage is what it is. I bought a Jeep truck because it is fun and functional. I wouldn’t care if it got 8 mpg. I would still buy it. Nothing I drive is this fun or functional!

True !
I wanted a pickup truck.....AND a convertible for beaching....This is the only vehicle that checked BOTH boxes !

 

[DaddyG]

Put 35's on my Overland and ran them on the 3.73 gears. Going uphill was painful as it stayed at 4k rpm to maintain. After the trip I called Rebel Offroad for gear change. Now 4.56 gears and much better performer. 4.10's are the minimum with 35's.

and if the dealer put 35's then they should have already changed the programming for tire size. Go back to the dealer and find out so you dont waste your money on a Tazer (Although there are many other niceties in the Tazer and you will need one if you change gears).

My gear change cost $1700 OTD. Expect to pay $500-800 per axle (depending on the gears) plus labor.

I swapped to 35" tires on my Max Tow....I could feel a slight decrease in "off the line" performance, so I went to the dealer to have the ECU flashed.....My dealership told me they could only reprogram for 33" tires since it was not a Rubicon..... ??

 

[Mac]

Winter fuel may also be a factor, I lost around 2mpg since summer.

 

[Vincent]

I had a gasser with 37's, manual trans and 3.73 gears. While 37's aren't really comparable to 35's, I cant imagine that you wouldn't need to regear to retain any semblance of factory performance and mpg's. There is no benefit to a tuner without doing lots of other performance mods and getting a custom tune..
Even with the tiny factory wheel/tire package I wasn't getting over 20, highway or town, best I was ever able to do with the 37's was just shy of 17 but that was straight highway 65ish basically flat grade or downhill with a tail wind! Anything marginally up hill, a head wind or speeds of 70 plus (read:normal conditions) and I was lucky to get 13.

All that said, you could try one of those throttle manipulators. It isnt gonna change any actual power numbers but could change the "seat of the pants feel" as it eliminates the lag in throttle response.

i'm running 35's and have the Pedal Commander, and it definitely makes a huge difference in bringing back the "normal" feel. I have 3.73 and i'm getting 18-ish with a light foot on the skinny pedal. On the highway, it plummets...

 

[Jeeperjamie]

I swapped to 35" tires on my Max Tow....I could feel a slight decrease in "off the line" performance, so I went to the dealer to have the ECU flashed.....My dealership told me they could only reprogram for 33" tires since it was not a Rubicon..... ??

That's crazy or not accurate I wouldn't think. Hendricks in Concord NC will flash for any size tire up to 37's. I haven't personally had it done there but that's what they told me. They put 37's on some of the Jeep's on their lot so maybe that's why.

 

[PyrPatriot]

I get 14 with mostly city driving even with it calibrated.

I get 15mpg city driving. Falken 35s are HEAVY. I can't say that $1500-2000 is justified in mpg savings.

 

[cgflyer]

Unfortunately these kinds of questions will be answered by people with differing opinions, different builds, different driving styles and conditions...everyone's mpg's are going to be different based on the above variables. I ran 35's on my Rubicon without a lift for 32,000 miles with a Pulsar tuner and averaged 18.5 mpg...straight highway for a whole tank, I got up to 21 mpg (all depending on the conditions wind, road, hills, etc.) I used the economy tune unless I was towing anything more than 1.000 pounds (empty trailer) then I would use the tow tune. I now have 37's with 3.5" lift on stock 4.10's and it is still comfortable to drive. I use the tow tune (I liked the performance tune, but not enough to justify 91+ octane). 4th and 5th gear are great now, 6th is still usable in many conditions...if I re-gear, I will only go to 4.56....This is huge debate. There are guys that have loud opinions on gearing they will say 4.88 or 5.13 with 37's is a must, but pay attention to how many members on here are actually active and posting...it is the same handful of opinions over and over yet there are 100's of thousands of Jeep owners doing their own thing. I can guarantee you that there are a TON of Jeeps on 35's with lifts and 4.10s doing just fine. If you are seeing 13-14 mpg, it may be your driving habits/style?

I am not digging anyone's opinion, but in the end they are opinions....some based on years of experience and knowledge and some based on surfing forums. $600 for a Pulsar, you do some math to see how long 1-2 mpg improvement would net you $600 in fuel savings.

 

[cgflyer]

I get 15mpg city driving. Falken 35s are HEAVY. I can't say that $1500-2000 is justified in mpg savings.

I second this...no offense to the Falken owners, but I HATED the stock Falken MTs...the 33" Falkens on stock rims weighed more than my 35" Patagonia MTs on my Procomp wheels. Tire and wheel weight make a huge difference and translate to "HP" gains without increasing actual power.

 

[cgflyer]

Yes, auto. Is there a tuner that you recommend?

There is a difference between tuners and programmer...tuners change the tune of the engine. Programmers change the programming of features and such like fog lights on/off with high beams, tire size, TPMS settings, etc....Tazer is a programmer, not a tuner. As far as I know, Edge/Superchips are the only tuners. Either the Pulsar, or the Traildash2

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