Jeep Wrangler Forum banner

1 - 20 of 39 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
Hey guys! I’m currently running a 2015 JKU Sport with 3.21 gears, a 4” lift, and 35 inch tires. I previously ran the stock 32’s just as a commuter car to and from school, but now that schools out, I decided to throw the 35’s back on. With that, I want to upgrade gears. I’m undecided between 4.10’s and 4.56’s. What’ll get me the best MPG with these tires? I’m not really concerned with power, I’m not expecting anything crazy, just better than the 9 city and 12 highway I get currently. Any other suggestions for mpg other than buy a Camry? 😂
 

·
Registered
Joined
·
3,042 Posts
I've got 4.10's and 315's, and my mileage varies between 17 and 18.5 driving rural upstate NY roads.
 

·
Registered
Joined
·
1,054 Posts
I really don’t know what the best mpg would be but I wouldn’t bother regearing to 4.10s. I would at-least do 4.56s. That’s said I went 4.88s. Truthfully if you are worried about mpg I would pull the lift and go back to stock. Those 35s and 4” lift are gonna kill your mpg. Post up a pick of your 4”lift with the stock tires.


Sent from my iPhone using Tapatalk
 

·
Super Moderator
Joined
·
4,897 Posts
When you move up to 35" tires fuel mileage will go down. Even with the same stock gearing.
The same applies to your lift. It hurts fuel mileage by making the vehicle less aerodynamic.
Typically with 35's the two common options are 4.56 gears or 4.88 gears. Either will work, with 4.88 gears delivering the better performance and 4.56 gears might deliver fractionally better fuel mileage on the highway. But the difference in fuel mileage between the two gears will be minor.
 

·
Registered
Joined
·
191 Posts
I have 4.56's with a 6 speed manual and 35's. I though about 4.88, and I am sure that they would have been fine, but I didn't want to shift 4 times leaving a red light to get through the intersection.
Either is fine. I would do 4.56 again. Gas is free these days compared to the cost of a re-gear.
 

·
Super Moderator
Joined
·
4,897 Posts
I have 4.56's with a 6 speed manual and 35's. I though about 4.88, and I am sure that they would have been fine, but I didn't want to shift 4 times leaving a red light to get through the intersection.
Either is fine. I would do 4.56 again. Gas is free these days compared to the cost of a re-gear.
The difference in rpms between 4.56 and 4.88 is not that big.
But glad you are happy with your gears.
 

·
Premium Member
Joined
·
1,088 Posts
I too have 35s w/6sp. I re-geared to 4.88s and feel the Jeep performs in the exact manner it did when factory new. Perhaps even a touch lower as I can sometimes pull out in 2nd. Crawling is off the chart awesome too! imho.
 

·
Premium Member
Joined
·
7,697 Posts
35's with 4.10 gears = 15.4 combined
35's with 4.88 gears = 14.5 combined

Performance difference night and day. Better than stock performance, period. And my MPG could be a lot better if I didn't like 2800 rpms so much.
 

·
Premium Member
Joined
·
3,647 Posts
I had 4.10 on my Rubi and 35's, and now I have 4.88 as I plan on going with 37" tires in the future.

From the way it feels, 4.56 would be ideal for 35's.
 

·
Premium Member
Joined
·
3,647 Posts
35's with 4.10 gears = 15.4 combined
35's with 4.88 gears = 14.5 combined

Performance difference night and day. Better than stock performance, period. And my MPG could be a lot better if I didn't like 2800 rpms so much.
That's about what I'm seeing with my new 4.88 gears, on 35's.

The new axle trusses don't help the aerodynamics either, and neither does switching from 5W-20 to 5W-30. But you gotta pay to play.
 

·
Premium Member
Joined
·
350 Posts
My jeeps are are JKUR's and came with the factory 4.10's They now sit:

2016 with 4.88's running 37" STT Pro's
2015 with 4.56's running 35" ATZ P3's

This is what's ideal to put you back to the stock Rubicon operating specs(when they come with 4.10's) per charts and real world experience. In theory you are putting no unnecessary/additional stress on components beyond what FCA has already said is acceptable by giving you a 4.10's as an option on a Rubicon with 32" tires from the factory.
 

·
Premium Member
Joined
·
884 Posts
That's about what I'm seeing with my new 4.88 gears, on 35's.

The new axle trusses don't help the aerodynamics either, and neither does switching from 5W-20 to 5W-30. But you gotta pay to play.
Yep, but it doesn't feel high revving like it did on the 3.21's.... no 'winding out' feeling... 2800-3500 "oops, didn't realize" ... options are great... upshift if its a bother - no issues with lower rpm bogging... Its nice taking off in 2nd, or rolling stop signs in 3rd gear with barely any if inital bog. The rpm's come fast and easy unlike 3.21's. It's like the engine is barely working.
 

·
Super Moderator
Joined
·
2,008 Posts
My stock 4.10’s and 35’s are good enough that I likely won’t re-gear.

But I won’t pay to re-gear to 4.10’s. It doesn’t cost anymore to go one more step up, I’d go 4.56
 

·
Registered
Joined
·
2 Posts
Discussion Starter #16
My stock 4.10’s and 35’s are good enough that I likely won’t re-gear.

But I won’t pay to re-gear to 4.10’s. It doesn’t cost anymore to go one more step up, I’d go 4.56

If you don’t mind me asking what mileage are you getting?


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
43 Posts
It would probably take 100k miles to break even on a gear change vs gas mileage. It does make significant difference in drivability. With 35's, nobody I know with 4.88 has said they wish they went with 4.56. I know a few with 4.56 that wish they went with 4.88. I have 4.88 and may swap in 5.13.... Comparing milage from one jeep to another is difficult. A lot of variables. Tire weight, rolling resistance, tire pressure and driving style are just a few.
 

·
Registered
Joined
·
4,232 Posts
In 2 weeks my 3.73's will be gone and my 4.56's will be in. I'll be driving very easy for 500 miles. It won't be a fair test but I'll be looking at MPG then. 70mph RPM should be about 2700 but won't see that for a while. Most of my miles are around town and that's where I hope to see the most change in pep and MPG.
 

·
Super Moderator
Joined
·
4,897 Posts
In 2 weeks my 3.73's will be gone and my 4.56's will be in. I'll be driving very easy for 500 miles. It won't be a fair test but I'll be looking at MPG then. 70mph RPM should be about 2700 but won't see that for a while. Most of my miles are around town and that's where I hope to see the most change in pep and MPG.
I know you have made up your mind, but you really sound like a better candidate for 4.88 gears.
 
1 - 20 of 39 Posts
Top