I was in denial but after driving up to Sacramento...

[Jeeperjamie]

I am on 37's with 4.10 gears and mine does pretty good. I averaging around 17-17.2 Mpgs and as long as I keep it under 75 I'm in 7th and 8th gear mostly. If I decide to stay on 37's I'll do 4.56 gears at the most if I decide to regear. If I make the decision to go 39's I'll end up with 4.88 gears.

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[Jeeperjamie]

I'd want 5.13 with 37s.

RPM will be 2,300-2,400 at 70 which is perfect.

That's where my RPMs are on 37's with 4.10 gears

 

[NC_Overland]

If you have plans to go to 37s then go 4.88. If sticking with 35s, then 4.56 will bring you back to stock.

 

[mdyucca]

... I need to regear.

A year of mostly city driving kept me blissful ignorant. Then a trip from South San Francisco to Sacramento, in mostly 6th gear, has brought me to the reality that 35s on 3.75 gears are not ideal.

Now my question to you good people, 4.11 or 4.88 Gears? Like I said, mostly city miles but that trip to Sac was a little unnerving.

I have attached a link that gives good insight into the difference between gear ratios. If you are not driving on the freeway 80% of the time I would go with the lower ratio.

 

[JTDay]

Do you have a Manuel transmission?

OP, might say it depends on his mood..

This gear calculator is really good:

https://www.jlwranglerforums.com/forum/threads/calculator-gear-ratio-tire-size-speed-etc.38206/

 

[Deleted member 22728]

4.88 for gas burners, 4.56 for diesel and HEMI.

 

[npgeorgeuw]

I'm on 4.88 gears with 35x12.5 inch tires and beefy rims (34.5 unloaded) and am happy. I spend a ton of time in 8th now compared to before and gained a tiny bit of mpg back from stock gears. I believe with my elevation changes and lack of towing that I will be fine going to 37s with this gearing. It was VERY much worth the cost to re-gear but I also added an air locker up-front so there's that, got a good discount on it since things were getting pulled open anyways. (or so I tell myself). My only complaint is that it spends very little time in lower gears now, maybe a little over-geared? When I am loaded up a bunch, though, I feel it's geared up just perfectly and it just seems to shift at way better points and power ranges. I'm not a mechanic though since it's more a subjective difference. I'd imagine at 4.56 I'd be perfectly happy with no load and no towing and not 37s.

 

[Jeeperjamie]

I was considering 4.88 but I'm curious now as to why not 4.56 if your not planning on going any taller than 37's. The 8spd does pretty darn well with 4.10 gears on mine. Did another video this morning of mine and I feel like 4.56 would be the sweet spot unless your towing a ton of weight then i could see 4.88 or 5.13, but for the average commute wouldn't 4.56 be closer to where the stock gearing is at? Just a question not trying to say 4.88 or 5.13 is a bad choice.

 

[Wheelin98TJ]

Never fear the gear. I vote 4.88's, especially if you ever tow, haul, or hit a significant amount of hills.

Worth repeating.

4.88 for 35s, 5.13 if you are thinking 37s someday.

Gain a little low end vs stock, but you're still only turning 2,400 RPM at 70 which is perfect.

I was considering 4.88 but I'm curious now as to why not 4.56 if your not planning on going any taller than 37's. The 8spd does pretty darn well with 4.10 gears on mine. Did another video this morning of mine and I feel like 4.56 would be the sweet spot unless your towing a ton of weight then i could see 4.88 or 5.13, but for the average commute wouldn't 4.56 be closer to where the stock gearing is at? Just a question not trying to say 4.88 or 5.13 is a bad choice.

Wind at your back? ? How much time are you spending in 8th gear? I couldn't see your tach for a lot of the video and your gear indicator isn't showing next to the odometer.

I live where it's pretty flat and mine does not like cruising under 2k RPM.

 

[Jeeperjamie]

Worth repeating.

4.88 for 35s, 5.13 if you are thinking 37s someday.

Gain a little low end vs stock, but you're still only turning 2,400 RPM at 70 which is perfect.


Wind at your back? ? How much time are you spending in 8th gear? I couldn't see your tach for a lot of the video and your gear indicator isn't showing next to the odometer.

I live where it's pretty flat and mine does not like cruising under 2k RPM.

The gear indicator is at the top where it has a D I got a Base Sport Max Tow and I was mainly in 7th and 8th for whole ride. This is rolling hills right on the Piedmont/Foothills section of North Carolina, I'm a hour and half from the Smokey mountains. Right now I'm averaging right at 18 since the weather has been in the mid 70's the past few days and not below 40 in the mornings. Been in the 50's the past 3 mornings.

Also no, wind was not at my back, a pretty calm morning and no I wasn't traveling down hill for the whole ride either.

I'm just on the fence on why not just 4.56. I've only been under 17 Mpgs on the colder mornings when it gets below 30 and that was only dropping the Mpgs to 16.8. Only twice it has gotten down that low and within a day or so I was able to get it back over 17. I feel like 4.56 would be the sweet spot with 8spd auto if your not planning on towing and stay with a lighter 37. Mine weigh 72lbs. This is how it's sitting currently

 

[XraytecH]

Do you have a Manuel transmission?

8 Speed Auto

On the trip back I switched to manual mode and shifted to 7th & 8th on flat roads, which in retrospect was probably a bad idea?

 

[AustinL911]

IMO:
35+auto = 4.56
35+man = 4.88
37+auto = 4.88
37+man = 5.13

 

[WILDHOBO]

IMO:
35+auto = 4.56
35+man = 4.88
37+auto = 4.88
37+man = 5.13

Unless someone tows a lot, then from what I gather, one step up with lots of towing, higher altitudes, and steep uphill grades. Basically, different recommendations for larger tires and using them as Jeeps and trucks, not mall crawlers looking for a bigger look (street daily driving). Am I wrong?

 

[Terry]

I have been studying this. I have 35s and the 6MT on stock 4.10 gearing. 4.56 is the minimum I would go to if I had to for gas mileage - that is what the JL Extreme Recon will run. I believe 4.88s are optional and will be the standard gearing on the JT Extreme Recon if and when it is ever offered. if I had to do it myself I would go to 4.88. Again - this is for 6MT vehicles. Different for automatics because they have more gears and more even ratio spreads...

I live right below the Cajon Pass in San Bernardino County. I climb this 4,000+- foot pass in my stock Rubicon going to the High Desert on I-15 all the time and the engine doesn't lag as the automatic shifts down when encountering grade changes (from little to as much as 15%) as I make the 20 mile trip over the pass.

 

[WILDHOBO]

I live right below the Cajon Pass in San Bernardino County. I climb this 4,000+- foot pass in my stock Rubicon going to the High Desert on I-15 all the time and the engine doesn't lag as the automatic shifts down when encountering grade changes (from little to as much as 15%) as I make the 20 mile trip over the pass.

I climb 4000ft frequently as well in our currently stock height, wheel/tire size rubicon. It does great, as it seems yours does. With the 37’s and lift going on next month, the 4.10’s would struggle big time. And we do those drives with a trailer.

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