Shift points - 35s

[mquinn13]

I remember reading during launch that dealerships can recalibrate the speedometer if you put larger tires on

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[Mattyp1214]

I have to disagree, I have 35’s Nitto ridge grapplers and noticed that the shift points are off.

First highway driving its very rare now that I hit 8th gear . I have been manually shifting lately just to compensate.

I was expecting a drop in MPG but now due to lack of shifting into a higher gear I’m getting around 14- 15 mpg around town a significant drop from the 25 mpg average I was getting . I was expecting a drop but I see the RPMs are always in high 2k range and not shifting to next gear as constant as the stock tires again as expected.

Just my observations. Not sure flashing for speedo correction, will help or not.

2018 JLU Sport White
17” Method matte black
3” Fabtech lift
35” Nitto Ridge Graplers
Build link
https://www.jlwranglerforums.com/forum/threads/project-jilly’s-white-jlu.7655/

Same foe me with same tires. I think mine is off as well. Need to buy a tazer and see if that helps or not

 

[1quick1]

Mine feels better after deal recal and I get 19+ mpg mostly city.

 

[Mattyp1214]

Mine feels better after deal recal and I get 19+ mpg mostly city.

19+ mostly city, I get 14.8. Is that due to the dealer recal you think? I wish I got that mpg lol

 

[1quick1]

19+ mostly city, I get 14.8. Is that due to the dealer recal you think? I wish I got that mpg lol

I do have a sport so my gearing is 3.45 but I truly do get 19+ on 315/70/17's at 5000+ altitude

 

[mwilk012]

Correcting the speedometer calibration absolutely corrects the MPG issue and shift points being off.

 

[Sinningdf]

Correcting the speedometer calibration absolutely corrects the MPG issue and shift points being off.

Did your local Jeep Dealer do the speedometer calibration via software and how much did it cost you after you installed larger tires?

 

[mwilk012]

Did your local Jeep Dealer do the speedometer calibration via software and how much did it cost you after you installed larger tires?

No my local jeep dealer is incompetent, I did it myself with the Tazer. It's very simple.

 

[TJEli]

Just to be clear... It doesn't "fix" anything with your actual fuel mileage. All it does is recalibrate the speedometer and odometer so the computer will show actual speed, miles traveled and MPG. All three are lowered by the percent height difference in tires. You can always calc it in your head if you want.

-Eli

 

[mwilk012]

Just to be clear... It doesn't "fix" anything with your actual fuel mileage. All it does is recalibrate the speedometer and odometer so the computer will show actual speed, miles traveled and MPG. All three are lowered by the percent height difference in tires. You can always calc it in your head if you want.

-Eli

The adjustment to the auto transmission's shifting is very noticeable, and I wouldn't be surprised to see it have an effect on mpg.

 

[jfox]

Just to be clear... It doesn't "fix" anything with your actual fuel mileage. All it does is recalibrate the speedometer and odometer so the computer will show actual speed, miles traveled and MPG. All three are lowered by the percent height difference in tires. You can always calc it in your head if you want.

-Eli

I was pretty excited about my new MPG.... then i read this. Went from high 16's to low 19's.... comment seams logical... why didn't I think about that?

 

[WranglerMan]

I was getting 21-22 mpg’s on stock rubber but once I went to new method wheels and 315’s my mileage dropped to 18-19 and I rarely see 8th gear, shift points seem to have recalibrated themselves but I still rarely see 8th, speedo was off by 5-6 mph at 70 so set tire size with Tazer and all is correct on speed

 

[Bearman95]

I have 315’s on mine and have noticed no difference at all other than The speedometer is off about 3 mph doing 60. I’m driving a Rubicon. I cannot even tell the difference in the ride since I went with The exact same tires that came stock except being in a 315.

 

[1quick1]

I have 315’s on mine and have noticed no difference at all other than The speedometer is off about 3 mph doing 60. I’m driving a Rubicon. I cannot even tell the difference in the ride since I went with The exact same tires that came stock except being in a 315.

There's definitely a difference between the Sahara/Sport and Rubicon.

Sport/Sahara = 31.5" tire to 34" 315/70/17 KO2 is bigger difference than the Rubi w/4.10's going from 285/70/17 to 315/70/17.

When I went stock Sport wheels/tires to stock Rubicon wheels/tires I was only off 1-3mpg but when I went to 315's it was off around 6mph at 65-70mph and it really didn't want to go into 8th gear.

I probably wouldn't bother paying the dealer to recalcibrate on a Rubicon but definitely would on a Sport/Sahara.

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