What gear ratio should I install in my Jeep Wrangler TJ / LJ? (and other re-gearing FAQs)

Steel City 06 said:
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Consider that a TJ Rubicon came with 4.10s and tires 2" or so smaller than yours, even with the NSG370. Those RPMs are perfect fine to run for an extended period; in some cases (like the 6-speed Rubicon and in the 3 speed autos) they did that from the factory.
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Consider that all TJ Rubicons came with 4.10 gears regardless of the transmission. There were three options, all with very different OD gears. Which one was correctly geared?

The 32rh ran about 3180rpm at 75rpm right off the assembly line. That should tell anyone all they need to know about what Jeep considered safe and acceptable.
 
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Tiros said:
Having read a lot here the recommendation seems to be 3k RPM @75 MPH. A lot of the info for gearing manuals is regarding the 5 speed. My TJ has a .84 overdrive NSG370 close ratio 6 SPEED, 4.0 and 33" tires. So are the recommended gear/rpm combinations in gear 5 @ 1:1, or Gear #6 @.84:1? Currently running a 3.07. One formula 33/30*3.07 = 3.37. So if factory was 30inch tires and I went to 33, that is 110% larger so 3.37 would be the actual ratio required to restore the rpm/gear to factory design? That does not seem right. I must be missing something.
Trying to decide on using 4:10 (LEFT) or 4:56 (RIGHT) I used 33" for my tire size in reaper, which I am now aware might actually be slightly smaller.
I don't crawl. Looking for best drivability and economy IE: A daily driver. Thanks for any and all advice!


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If 33’s are your final tire size, 456 with the NSG-370. Your calculations are pretty correct, but that’s not the entire issue. You’ll be deeper geared than from factory, but I guarantee you’ll be happy.
 
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Steel City 06 said:
4th gear on 3.07s is almost exactly equivalent to 6th gear on 4.56s. So if driving around and on the freeway and 4th gear seems like a decent gear to use in the highway, 4.56 gears will work very well.
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This is a great idea, thanks!!
So I find that 4th is not quite enough for the highway, sometimes I need 5th.
I understand that using 4.56, 2970 rpm@75mph is considered "perfect" but I think its too much considering 75 is speed limit on many roads now. The 4.10 will give me 2670 (300 less) at the same speed and will make 1st gear more usable. Matter of fact the 6spd/4.10 would be geared exactly the same as the 5 sp/4.56 for the first 2 gears. In top gear the 6 sp/4.56 will rev 200 higher than 5sp/4.56 @75mph and 300 higher than the 6spd/4.10. It seems like the only thing to give up is 300 rpm @75mph. I really don't understand why the 5 speed recommended is 4.56 and the lowered geared 6 speed is the same recommendation.
 
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Tiros said:
This is a great idea, thanks!!
So I find that 4th is not quite enough for the highway, sometimes I need 5th.
I understand that using 4.56, 2970 rpm@75mph is considered "perfect" but I think its too much considering 75 is speed limit on many roads now. The 4.10 will give me 2670 (300 less) at the same speed and will make 1st gear more usable. Matter of fact the 6spd/4.10 would be geared exactly the same as the 5 sp/4.56 for the first 2 gears. In top gear the 6 sp/4.56 will rev 200 higher than 5sp/4.56 @75mph and 300 higher than the 6spd/4.10. It seems like the only thing to give up is 300 rpm @75mph. I really don't understand why the 5 speed recommended is 4.56 and the lowered geared 6 speed is the same recommendation.
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What tire size are we dealing with? I am not aware of a scenario where both the 5 and the 6 speed get the same recommendation. The 6 speed is typically one gear numerically higher because of the OD gear.
 
I have 33" tires.
I just notice the chart at the top of this thread shows 5spd/4.88 for 33". I have seen the 5spd/4.56 far more commonly recommended for 33 in other places, including this forum: https://wranglertjforum.com/threads/gear-ratios-for-33-tires.34508/
It is for this reason I think many suggest 4.56 for 6 speed as well.
I have also read a few who say 5spd/4.88 with 33 is to much rpm on highway. I think 6spd/4.10 is a closer match to the 5spd/4.56 setup that seems ideal.
 
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Tiros said:
I have 33" tires.
I just notice the chart at the top of this thread shows 5spd/4.88 for 33". I have seen the 5spd/4.56 far more commonly recommended for 33 in other places, including this forum: https://wranglertjforum.com/threads/gear-ratios-for-33-tires.34508/
I have also read 5spd/4.88 with 33 is to much rpm on highway. I think 6spd/4.10 is a closer match to the 5spd/4.56 setup.
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For many years, the internet wisdom (which includes a few long timers from here) did not understand that the TJ wasn't necessarily geared well from the factory, that different transmissions required different gearing, or that there are certain common tire/trans combinations that simply can't be geared low enough. Add that to a persistent false belief that 4.88 is as low as one should go, which created the flawed logic that subsequently smaller tires needed subsequently higher gears, and you have a mess of bad recommendations floating in the ether that will never go away.

I have been pushing 3k at 75 for years, because it is relatively easy to comprehend and it works well. But again, is you look at the early TJs with the 32rh, we still aren't gearing low enough.
 
From my own experience. I have TJ 2004, 4.0, 42RLE, 4.56 gears. I am using 245/75R17, which is 31.5 inch tires (in reality 30.5). Getting 2250 RPM at 65MPH, and around 2450 at 70MPH. I should have 5.13, which would give 2535 at 65MPH and 2750 at 70MPH. I am not going to spend money on regearing it, but I wish i would.
So, if you have 42RLE and plan to regear, go as deep as you can.
 
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I need an advice on my gear ratio setup, I'm driving a manual NSG370 6 speed 2006 TJ currently on 275/70R16 tires with 3.73 gear ratio from factory and a 2.5" lift kit. I have Dana 44 trac-lok in the rear with Dana 30 in the front. This is my DD and once or twice a year I take it off-roading to the desert, mainly I drive short trips in the city with some long drives occasionally. I've been reading that with the tires I have I need 4.11 gear ratio for optimum performance/fuel economy, is that really the case for my use mentioned above? pls note I have no plans to go for bigger tires in future

I tried using the grimm calculator, I'm not an expert, but seems like the 3.73 is doing fine for my dd use compared to the 4.11 therefore will really appreciate to hear your thoughts.

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Ziggy said:
I need an advice on my gear ratio setup, I'm driving a manual NSG370 6 speed 2006 TJ currently on 275/70R16 tires with 3.73 gear ratio from factory and a 2.5" lift kit. I have Dana 44 trac-lok in the rear with Dana 30 in the front. This is my DD and once or twice a year I take it off-roading to the desert, mainly I drive short trips in the city with some long drives occasionally. I've been reading that with the tires I have I need 4.11 gear ratio for optimum performance/fuel economy, is that really the case for my use mentioned above? pls note I have no plans to go for bigger tires in future

I tried using the grimm calculator, I'm not an expert, but seems like the 3.73 is doing fine for my dd use compared to the 4.11 therefore will really appreciate to hear your thoughts.

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If you're happy with the performance leave it alone but if you're struggling on large grades you may see some value. Personally I'd likely save the 2k and buy something else on my list. Like bumpers, skids, armor, winch, recovery gear etc...
 
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Alex01 said:
If you're happy with the performance leave it alone but if you're struggling on large grades you may see some value. Personally I'd likely save the 2k and buy something else on my list. Like bumpers, skids, armor, winch, recovery gear etc...
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Agreed
 
Ziggy said:
I've been reading that with the tires I have I need 4.11 gear ratio for optimum performance/fuel economy, is that really the case for my use mentioned above?
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just a note of interest: the factory paired 4.11s with 245/75-16 (30.5x9.5-16) tires
Ziggy said:
I tried using the grimm calculator, I'm not an expert, but seems like the 3.73 is doing fine for my dd use compared to the 4.11 therefore will really appreciate to hear your thoughts.
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not that it matters all that much but for accuracy input the measurement of your tires from the ground up to the center of the wheel and double it (not the advertised diameter)
 
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Alex01 said:
If you're happy with the performance leave it alone but if you're struggling on large grades you may see some value. Personally I'd likely save the 2k and buy something else on my list. Like bumpers, skids, armor, winch, recovery gear etc...
Click to expand...

I thought I was happy with the performance until now as my rear dana 44 spider gears are worn out and needs to be changed so I decided to go with Yukon Dura Grip but it has two options 3.73 and below OR 3.91 and above therefore the decision of which gear ratio I will be running is crucial so I don't have to spend more than what is required. Additionally, all this time I thought I had a good mpg till I saw some of the threads here where they make 15-20 mpg on their TJ while mine a full tank (19 gallons) gives me 350km (217 miles) which was very shocking. that being said, I'm in this forum now to get more clarity if I really need the 4.11 and if that will help me get the best performance from my car and higher mpg.
 
L J said:
just a note of interest: the factory paired 4.11s with 245/75-16 (30.5x9.5-16) tires

not that it matters all that much but for accuracy input the measurement of your tires from the ground up to the center of the wheel and double it (not the advertised diameter)
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Interestingly, when I used this method to measure it gave me 30.5 approximately
 
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Ziggy said:
Interestingly, when I used this method to measure it gave me 30.5 approximately
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it doesn't make a big difference but for the sake of precision one needs to account for the tire "squish"
 
machoheadgames said:
The 245/75/16s would measure smaller than 30.5, more like 29.5. I’d rather 4.10 than 3.73 for sure but I don’t think I’d pay money for that swap. I’d probably step it up to 33’s and go to 4.56.
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mines are 275/70r16 not 245/75/16 therefore 30.5 (or 31.2 if I go with the calculator conversion) seems like a right size
 
Ziggy said:
mines are 275/70r16 not 245/75/16 therefore 30.5 (or 31.2 if I go with the calculator conversion) seems like a right size
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Whoops, I thought yours were 31.5 off the top of my head. Being 31.2 I would expect them to be about an inch short actual, around 30.2. But on a tape measure or however you measured it’s really splitting hairs anyways as those are miniscule differences.
 
Hi all, I've got a gearing question and figure I'll start here first before posting the millionth "what gear ratio should I get" thread.

I've seen a lot of conflicting advice for my situation on what gear ratio too go with. I have a 1999 4.0 with the 3 speed 32rh trans. My Jeep is currently on 33s and it's an absolute dog at highway speeds. At 65mph right now my rpms are right around 3000rpms.

Admittedly this is a fairly old thread, but it seemed like the prevailing advice for the 32rh/33"tire combo was to go no deeper than 4.10 gearing? Is that still the case? If my rpms are already about 3000 at 65, is going deeper to 4.56 or 4.88 recommended or would that put me way too high in the rpms on the highway?
 
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Use GPS to determine if 65 is actually 65 or more. If it’s actually 65, then you are close to the rpm of 4.10 as it is. The speedo is likely incorrect, and you probably have 3.73s and probably are going faster than 65. In other words, you need to figure out what you actually have first. 4.10 and 33’s is generally regarded as a good combo.

You also may have an adjustment issue like you might need to adjust the bands and TV cable to make sure it’s shifting adequately which will affect drivability big time.
 
machoheadgames said:
You also may have an adjustment issue like you might need to adjust the bands and TV cable to make sure it’s shifting adequately which will affect drivability big time.
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Thanks, will do on verifying actual speed with GPS.

Can you please elaborate on what you mean by the above? What are the bands and TV cable your referring to, transmission related?
 
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