37's on a Rubicon...

[landshark99]

My 2019 JLUR 2.0 had 35 KM3s on in the first three months( 2 years), did not think I needed to switch out the stock 4.10, did lose 8th most of the time and my mileage averaged around 14-16. A couple of months ago I went with 37 KM3s and re-geared to 4.88s, I have 8th back, my mileage is now around 18-20, like it better off road, especially in 4high and overall it feels as quick as it was when stock on the 33s

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[Chief_Dan]

going from 35's to 37s?

Well, if you have an Xtreme Recon edition, then it should have 4.56 gears & needing more may not be necessary.

If you don't have the XR, which I am assuming, then the 4.10s are probably not bad with the 35s. So, it will more depend on your use whether you need 4.88s or 5.13s.

Friend of mine has 37s on his JLUR & reset the instrument cluster with a Taser JL mini. His 2019 is just about like my 2020, same 3.6L & automatic. I can tell a difference, but I have to admit, it isn't real bad. But, if towing or in the hills, & overall acceleration, it would be better if he did regear. But, it still isn't that bad, but I would want to regear. When he had 35s on it, before the lift, I couldn't really tell a difference from mine, which is still on the stock 33s. So, if you're using a heavy tire, a regear may be more apparent. But, if getting a 37 in a lighter weight, you "may" be okay.

More or less though, it will come down to how you use your Jeep & how you feel about it.

Hope this helped some.

 

[Guy Jepsy]

Went to 37s on my RJLU and tried staying with stock gearing. Not bad on the flat (stayed in 7th at highway speeds) but first trip where I was doing steep switch-backs it bogged down. Changed to 4:88s the next week. Now acceleration is better and Jeep is much happier on the trails.

 

[MattT69]

These comments need to be grouped into two Rubicon perspectives.
*edit: the following groups are for the 2 door 4.10 JLRs
1. NA V6 will require a regear regardless
2. Turbo I4 will not require a regear but is helpful for 4 door option

**edit: add the following groups for the 4 door 4.10 JLRUs
3. 4Xe 2L Turbo no regear required
4. 3.L Diesel no regear required
6. 392 v8 no regear required

***edit
All the above assumes no added weight and below average weighted 37s.

I fall into the 2nd camp. I regularly run through all 8 gears as you would normally. I Still get 20mpgs on 37s and 2.5 lift... BUT I am in the very limited and unpractical 2-door 2-seater JLR Club. So that might be why I'm getting such good performance with 4.10 gears. I also run the KO2 which are the lightest (Load D) and smallish sized 37s, so that is another benefit to take into consideration.

 

[colby]

My 2019 JLUR 2.0 had 35 KM3s on since in the first three months( 2 years), did not think I needed to switch out the stock 4.10, did lose 8th most of the time and my mileage averaged around 14-16. A couple of months ago I went with 37 KM3s and re-geared to 4.88s, I have 8th back, my mileage is now around 18-20, like it better off road, especially in 4high and overall it feels as quick as it was when stock on the 33s

Thanks for sharing this. I upgraded to 37s two days ago and immediately wanted to regear to 4.88s

 

[OffroadCalling77]

I’m running BFG K02 37s on my 392. While I only have 3.73 gearing, my engine does produce a bit more torque than the 3.6 and 2.0.

With that said, I do plan to go with larger tires at some point and will probably go to 4.88s, especially towing the trailer.

 

[offcamber]

I've been running 37's since about 3 months after buying my JLUR in Feb 2018 on the stock 4.10's. I always intended to regear, but I've never felt like I needed to do so. I have 50k miles on my Jeep. I've driven it to Florida once and to Vegas last summer. On the highway I average almost 20mpg (literally 19.9mpg). It doesn't seem to hunt for gears, passes with ease, etc. I've used the built in Tazer 0-60 timer on the dash and it hits 60 from 0 in about 7.5 seconds so I have no complaints.

 

[MallBrawler]

I did not re-gear for the 6000 miles that I had 37's on. My intention was to regear, but I kept putting it off repeatedly, and chose not to deal with it because a lot of shops were backed up. Ended up going 6000 miles without regearing before I decided to order a 4XE (and started unmodding the car).

I did not run into major issues, although this doesn't mean that mechanical problems wont occur in the future. Its worth noting that I have a 6MT and 6th gear is basically completely useless and most highway driving was on 5th gear. I also went on a few trails, one of them a badge of honor. No problem in 4H or 4L. Aside from that, everything felt very normal.

 

[TJJL19]

As long as we are talking tires, gears, on a Rubicon, I was wondering what would happen if I bought a 392, with XR package and went the opposite way with tires?
My Boxer(dog) is getting old and I don't want to make it harder for her to get into any Jeep, I own.
I do a lot of Suburban driving and with the lower height, with stock sport(17) tires and rims what would happen to gearing, etc.
When I wanted to go crazy off road, I could put the XR tires back on.
So what do you think about this idea? I have a extra set of stock rim and tire from my 2019, JLU, Sport S

 

[lowmpg]

I've been running 37's since about 3 months after buying my JLUR in Feb 2018 on the stock 4.10's. I always intended to regear, but I've never felt like I needed to do so. I have 50k miles on my Jeep. I've driven it to Florida once and to Vegas last summer. On the highway I average almost 20mpg (literally 19.9mpg). It doesn't seem to hunt for gears, passes with ease, etc. I've used the built in Tazer 0-60 timer on the dash and it hits 60 from 0 in about 7.5 seconds so I have no complaints.

Wow. That is interesting and thanks to all that responded!! From what was said it seems the general experience is, the Rubicon doesn't require you regear it for general purposes. Again, thanks everyone!!

 

[Zandcwhite]

As long as we are talking tires, gears, on a Rubicon, I was wondering what would happen if I bought a 392, with XR package and went the opposite way with tires?
My Boxer(dog) is getting old and I don't want to make it harder for her to get into any Jeep, I own.
I do a lot of Suburban driving and with the lower height, with stock sport(17) tires and rims what would happen to gearing, etc.
When I wanted to go crazy off road, I could put the XR tires back on.
So what do you think about this idea? I have a extra set of stock rim and tire from my 2019, JLU, Sport S

You definitely won't need to regear. You'll see slightly higher rpms on the freeway, but our 2nd Overdrive (8th gear) is so tall it really doesn't matter much. With 4.56 gears and 31's you'd only be at ~2300rpm at 70mph. Certainly not over revving or high rpm by any means. I won't comment on how ridiculous a 392 Rubicon XR is going to look on little street tires as your motivation for doing so is about the only justification I can get on board with.

 

[bacon392]

As long as we are talking tires, gears, on a Rubicon, I was wondering what would happen if I bought a 392, with XR package and went the opposite way with tires?
My Boxer(dog) is getting old and I don't want to make it harder for her to get into any Jeep, I own.
I do a lot of Suburban driving and with the lower height, with stock sport(17) tires and rims what would happen to gearing, etc.
When I wanted to go crazy off road, I could put the XR tires back on.
So what do you think about this idea? I have a extra set of stock rim and tire from my 2019, JLU, Sport S

You’d be better off buying side Steps or a even a dog ramp.

XR has a suspension lift in addition to the 35s. Going to 33” only loses you 1”, but you still have 1.5” of suspension over stock. Additionally, you’re going to have (too) high gears for those tires.

Larger tires are the whole motivation for everything in the XR kit : suspension, gears, fender extensions, tire carrier, and the tires themselves. Just don’t get that package if you want a lower jeep.

just my $.02

 

[Zandcwhite]

Wow. That is interesting and thanks to all that responded!! From what was said it seems the general experience is, the Rubicon doesn't require you regear it for general purposes. Again, thanks everyone!!

We have been on 37's for 30k miles, recently went to 38's. We've wheeled all over the western states, multiple 1-2k mile road trips, moab twice, telluride, OR, AZ, and all over CA on the stock 4.10's. The 2.0t is still quick and fun to drive. Average mpg is ~17, not great but not terrible by any means. People get hung up on 8th gear (which me do see pretty regularly by the way), but fail to realize that no other wrangler before had such a ridiculously tall 2nd Overdrive gear to begin with. Our 7th gear is the equivalent of every other OD transmission ever offered in its highest gear. If we are talking pre-overdrive Era that is our 6th gear and yet people still drove around just fine? Couple that with the fact that our 1st gear is so low in comparison to every auto ever offered in a wrangler (a jk on 5.13's had the same crawl ratio/ 1st gear drive ratio, an early tj would need 6.72 gears to match), regearing is 100% optional in my opinion.

 

[Zandcwhite]

My friends have a tour company in Colorado. Their guide Jeeps are JKURs running 37s / 5.13s while their client Jeeps are JLURs running 35s / stock 4.10s. Know I’m comparing myriad apples and oranges, but the JKURs want to run away from the JLURs in 4L.

I'm going to call bs. It is simple math (assuming both rigs have automatic transmissions). The 4.7 1st gear in the JL equates to a 77.08 crawl ratio with 4.10's. The jk 3.59 1st gear in the JK with 5.13's gives them a 73.66 crawl ratio. Negligible difference. Combine that with having larger tires on the JK it has a gearing d I disadvantage in that scenario. The guides are running away from the customers based solely on experience and familiarity with the terrain.

 

[lowmpg]

Well now that I viewed the tire weights, turns out my current Falken WildPeak M/Ts at 35/12.5/17 weigh about 8lbs more than the 37/12.5/17 KO2's I want to go to, so no problem with weight I guess

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