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Gearing for 35's

20K views 144 replies 46 participants last post by  Reave 
#1 ·
What axle gearing would you suggest on a 2014 JKU with 35's that will likely never see any real offroading?
 
#2 ·
#3 ·
4.56 unless you are towing in the mountains...then 4.88.

EDIT- I have stock 4.10s with 35 and it is not enough in the mountains and at altitude. Going up Vail Pass (~9,000-10,000 ft) my JK (with a passenger and some luggage) struggles to keep 60-65. It even jumps to a screaming 2nd gear if I try to push it.
 
#9 ·
I live at 3300 feet elevation and mostly am under 8000 feet on road and 10000 feet off road. In Montana everything is either up or down and I have 35's and 4.10's (2014) and never had an issue. I don't pull a trailer tho. I guess a person needs to be honest with themselves and determine how often are you going to be driving at extreme elevations pulling a trailer? if once or twice a year not sure if it is worth changing gears. I think a person should consider where most of their daily driving will be when considering gearing as gearing has more effect on road then off in my experience.

Colorado is rare in that a person can drive at high elevation on a routine basis but not many places are like that. Montana is mountainous but we don't have those high paved passes like Colorado so here I can only think of one paved road over 10,000 feet most passes are under that by a fair amount.
 
#11 ·
Depends on the transmission and the driver. I've got 4:10's and the 5-speed auto. With 33's I think it's wound a bit tight. I live at 4500 feet and I'm often up at 7000 to 8000 feet. I think 35's would be perfect. Again, it's a subjective thing and it does depend on how often you drive at elevation.

My advice is to try to drive different Jeeps. A Willys on the stock 32's with 3.73's is about the same as 4.10's and 35's. A stock Rubicon is about the same as 4.56's and 35's.
 
#12 ·
Agree, I see a bunch recommending 4.88's with 35's but with the 3.6L it would be insanely overgeared in the flatlands. Most could get by with the 4.11's on 35's in the plains and never have issues. If you have the 3.8L then all bets are off.
 
#13 ·
I have a 2 door on 35's with 3.21 gears and a 6 speed.

Around town its fine. On the freeway you slow down in 6th floored. 5th has a slight idea of accelerating but 4th feels good. I think these engines would love to be at 2500-2750 in 6th. So I am going to be going for 4.88's so I wont have to drop gears on hills and what not all the time. The extra 250rpm at 70 will be good and I could always cut back to 65 to keep the rpms down and mpg up.

Better to be geared for performance than undergeared and have to do it again because you got 1" taller tires or heavier bumpers or something.
 
#15 ·
Looks like OP lives in Utah, I don't think the terrain is as severe as Colorado - IIRC, CO has 42 peaks at 14,000+ feet, passes at 10,000 feet. If you have a Rubi with 4.10 gearing you should be ok with 35s for a DD. If you don't have a Rubi, then regear to 4.56. Labor is the largest cost in a regear, but there is enough of a price difference between 4.10 and 4.56 R&P that 4.10 should never be a consideration. I just went from 32s to 33s (alloy rims to steel, so 30+ pounds heavier each wheel) on 3.73 gearing, this is ok. 35s are in the plans a few years down the road, I would never keep the 3.73 gears with the 35s.
 
#16 ·
Although, the gear ratio obviously impacts performance and fuel economy across the board, it's biggest impact is at highway speeds so unless you only drive around town,gear ratio is even more important if you stay on the pavement. When you drive off road you can justify suboptimal performance on the road to get what you need off road.

Use the gear charts above to select the best ratio for your needs but as OD said 4.56 is the consensus best match for 35" tires.
 
#18 ·
I live at sea level. But that doesn't necessarily mean much. I spend significant time above 5k. The steeps in the PNW are pretty much as extreme as they get anywhere. Local relief, as measured from peaks to adjacent valley floors can exceed 6k (10k if you include Mt Rainier). Washington state has some of the largest mountains in the world in terms of rise above base, total volume and glaciation. For that matter, the top 5 most heavily glaciated peak systems in the lower 48 states are all in Washington. Hey Colorado, put that in your pipe and smoke it!

Here's a tasty little fact: Mt Rainier rises 600' farther above its base and is more than 7.5 times larger than Mt Everest in terms of volume. By those measures, it is the 6th largest mountain on earth. Of course, Mauna Loa, in Hawaii, is roughly 95 times that of Everest ... just counting the area above sea level.
 
#19 ·
My 2014 JKU auto came from AEV with 35's and 4.10 gears. This combination worked very well till I re-geared to 4.56 for my 37's.
 
#23 ·
Goodyear DuraTracs looks pretty true-to-size though I have not measured them. My Goodyear MTRs were 35" but when aired to 28 psi on the vehicle, they measure at 34.5. I have also seen the Firestone MTs that seemed a tiny bit taller than my MTRs side by side. The KM2s may run closer to 34", from what I read.
 
#24 ·
My MTRs (which are pretty new) measure 34.75" on the vehicle. I have 4.10 gears and my RPMs at 70mph are just above 2600 (quite a bit different than the chart above). That's on a 2013 with an automatic. So far, I have no complaints. I live at 6500' and pull a camper and a snowmobile trailer pretty regularly.
 
#26 ·
I have two friends- one has an 18" rim size while the other has a 17" wheel size. They measured their DuraTrac 35s to 34.5" and 34" (respectively) at 30 PSI mounted.
 
#30 ·
I just got my '14JK 6 Speed back today (with 35s) where I re-geared from 3.73 to 4.88. WOW. Absolutely worth it. I've only got about 100 miles on it, however I can really feel the difference and I got my 6th gear back. I live on the Seacoast, however I go up to the mountains often. Also, I feel this will be so much better on my clutch and leg when rock crawling vs. the 3.73 I had, I felt that was just burning my clutch up.
 
#32 ·
4.56

I have some Yukon 4.56 gears waiting to go in with my 35's on. Just waiting on the ARB locker.
 
#35 ·
I am definitely going 4.88 with my 6 speed.

The 3.21 and 35s are killing me. I use 5th exclusively and do frequently drop to 4th. So if I can get a bit higher rpm in 6th from regearing. Like 2600-2700 at 70 I will be able to pull mild grades with pedal.
 
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