Comments on running 37s on Rubicon Extreme with 456 gears

[trekster]

I've ordered a 2022 RubiconExtreme, originally a 2021, changed it to 2022 because 9 weeks and still collecting parts....... How do 37s, affects performance on the highway and off road?

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[Outrun]

Probably the perfect combination.

 

[trekster]

Probably the perfect combination.

 

[trekster]

Thanks, I forgot to ask about the lift, hoping to stick with the Extreme lift from Jeep.

 

[Zandcwhite]

35’s to 37’s is a very small change. The final drive ratio will be almost equal to a stock rubicon with 4.10’s and 33’s. Approximately 1950rpm at 70 mph. As far as handling, assuming the same tire is used, will be a negligible difference. Even off road the difference isn’t huge, unless you are going with a more aggressive tire. If you are stepping up from the KO2 to a hybrid tire or full mud terrain then the off road difference will be huge. We road trip our JLUR all over on a 37” extreme terrain, and my wife daily drives it, but it’s not for everyone. They are a little louder on the street, wet traction suffers a little, I hear traction in ice is really bad (not an issue in CA) but in the mud, deep snow, soft sand, loose dirt, etc any mt will be vastly superior to the KO2.

 

[Rodeoflyer]

I dunno man, going from 33's to 35's I didn't really feel that much. Once I installed 37's I knew immediately the 4.10 gears weren't sufficient. I guess it really depends on how you use the Jeep and where you live. If you live at sea level and mostly wheel flat terrain under 1000ft of elevation you'll be fine. If you off road at 10k+ feet (like me) even 5.13's are just barely sufficient imo.

Also, if you have the diesel or turbo 4 you might be fine with it. The V6 just loses so much oomph at elevation I don't feel that I'd be ok even with 4.56's.

I just noticed you're in Golden lol. Well.. then what I said def applies to you.

 

[trekster]

I dunno man, going from 33's to 35's I didn't really feel that much. Once I installed 37's I knew immediately the 4.10 gears weren't sufficient. I guess it really depends on how you use the Jeep and where you live. If you live at sea level and mostly wheel flat terrain under 1000ft of elevation you'll be fine. If you off road at 10k+ feet (like me) even 5.13's are just barely sufficient imo.

Also, if you have the diesel or turbo 4 you might be fine with it. The V6 just loses so much oomph at elevation I don't feel that I'd be ok even with 4.56's.

I also live in Colorado, I'm getting the torque V6. We well Moab, Spring Creek some of the rougher trails in Colorado. My 4 Door JK Rubicon V6 35s 5.13 were awesome wheeling, but terrible on the highway. The reason I made the change.

 

[conFUcius]

37s on 4.88s or 5.13s are ideal. I’m sure you’ll do better on 37s with 4.56 vs. the 4.10s but try and drive someone’s set-up that has been re-geared. A lot of people think they are ‘fine’ not re-gearing but they have never driven an appropriately geared Jeep. That being said, I wouldn’t prioritize re-gearing from 4.56 right away since the OEM ratio on that XR package would likely make it more tolerable for now.

 

[Rodeoflyer]

I also live in Colorado, I'm getting the torque V6. We well Moab, Spring Creek some of the rougher trails in Colorado. My 4 Door JK Rubicon V6 35s 5.13 were awesome wheeling, but terrible on the highway. The reason I made the change.

Can you elaborate on 'terrible'? Were you running full MT type tires and what brand (some are more tolerable that others).

The JL has a wider powerband and more gears than the JK's did so you can't really compare the two.

As for mpg, I lost about 1/2mpg when I went to 35's and another 1mpg when I upgraded to 37's but I'm running Nitto Ridge Grapplers which are a hybrid/milder pattern and very low noise. They're perfect for central CO wheeling imo. We don't really have mud or soupy stuff here.

 

[trekster]

Can you elaborate on 'terrible'? Were you running full MT type tires and what brand (some are more tolerable that others).

The JL has a wider powerband and more gears than the JK's did so you can't really compare the two.

As for mpg, I lost about 1/2mpg when I went to 35's and another 1mpg when I upgraded to 37's but I'm running Nitto Ridge Grapplers which are a hybrid/milder pattern and very low noise. They're perfect for central CO wheeling imo. We don't really have mud or soupy stuff here.

The biggest issue with my JK was the transmission. It was a 4 speed, I believe auto, it was continually shifting up and down and had to run a high RPM on the Highway. This is the main reason I’m buying the JL. This is with the 35” tires and I was wrong earlier, my gears were 538.

 

[Carlton]

Reprogram with a Tazer and it will be fine.

 

[Jeepeto]

I’ve got the Xtreme Recon with 37s and find it to be acceptable. Not perfect, but acceptable. I think my main issue is due to wind resistance. 3.5” lift and 37s make it a lot to push over 75mph in 8th.

 

[Jamrock]

Generally speaking heavier tires will reduce your gas mileage since it takes more effort to push them around.

You may also want to consider some type of tailgate re-enforcement since the spare tire will weigh significantly more than the stock tire. Make sure the spare tire fits snugly against the Jeep. If your spare tire is moving around, it will put more strain on the tailgate.

When you add a lift, make sure that you adjust the lower control arms to bring your Jeep's caster back in line. Take a look at the video on Jeep geometry.

Heavier tires do tend to put greater pressure on your suspension components so things like ball joints might wear more quickly.

Having said this, lots of members run 37's with no issues. Just be aware of the compromises that you will have to make with larger tires.

 

[trekster]

Great information! Thank you. It sounds like 4.88 or 5.13 are ideal but the 4.45 should be ok temporarily. I saw a Rubicon Extreme 4 door at my dealer. Looks great, lift is higher than I expected above the stock Rubicon, but the front bump stops are huge, about 7" tall! So the upward travel will be limited by these.

 

[guarnibl]

Great information! Thank you. It sounds like 4.88 or 5.13 are ideal but the 4.45 should be ok temporarily. I saw a Rubicon Extreme 4 door at my dealer. Looks great, lift is higher than I expected above the stock Rubicon, but the front bump stops are huge, about 7" tall! So the upward travel will be limited by these.

IMO, I don't think it's going to be worth re-gearing if you have 4.56's from the factory. The 8 speed auto is just too damn good. You will be permanently fine at 4.56's, even on a heavy 37.

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