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Discussion Starter · #1 ·
I am having trouble with my jeep not being able to climb hills on and off road without down shifting at least two gears, I believe it has something to do with the over sized tires and the final gear ratio
 

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So, I guess that begs the question....

What size tires do you have, and what gear ratio in your diffs???

Hoss
 

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Discussion Starter · #3 ·
So, I guess that begs the question....

What size tires do you have, and what gear ratio in your diffs???

Hoss
I don't know the difference just got the jeep last Friday, tire size is 35x12.50r17. When driving home from salt lake city at 70mph I would be I. 6th and have to drop to 5th the 4th and even 3rd
 

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If you drop to 33's, you'd want 4.56 gears.

I just realized you said it's a Rubicon in the title, are you sure? If so, it should have 4.10 gears already, and your gearing shouldn't be that off..

Possible plugged cat?

Hoss
 

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Discussion Starter · #9 ·
If you drop to 33's, you'd want 4.56 gears.

I just realized you said it's a Rubicon in the title, are you sure? If so, it should have 4.10 gears already, and your gearing shouldn't be that off..

Possible plugged cat?

Hoss
Lower gear it runs like a tiger with a burning tail, 4 5 6 is where it is lacking. Online search says that it has 3.73 gears in it stock. If that is true would you recommend 4.1 or 4.56
 

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Since you have a 2010, 4.88 would be good and really 5.13 would be better.

When I had my 2007 JKU automatic, I had 315/70-17 tires with 5.13 gears. This was a good set up.

I traded it in for a 2014 JKU automatic. Once again, 315/70-17 tires. I went with 4.88 gears this time due a different engine and transmission. I could have went with 4.56 with this set up, but I wanted a little bit extra for towing an enclosed trailer. Without the trailer, it drives like a sports car.

You can go on Jeep website and there is a link For Owners. You can put in your vin and it will tell you everything about your Jeep when it left the factory such as gear ratio and tire size.
 

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Ok 4.88 sounds good but what kinda of fuel mileage would I see on road, nearest Walmart is 100 miles each way
If MPG was an issue going 35s is trouble. Gears will help but you are kinda locked in on street 35s. just to get to wall mart must be some rough roads.....
 

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If MPG was an issue going 35s is trouble. Gears will help but you are kinda locked in on street 35s. just to get to wall mart must be some rough roads.....
Exactly this

35’s bring terrible fuel economy to a JK and the first generation JK is slightly worse than the second generation about this.

Stock gearing with 35’s means awful fuel economy.

Deeper gearing with 35’s improves the fuel economy but is still pretty bad.

Stop and go traffic is where 35’s especially kill fuel economy. It’s not the steady 65 mph.

Since your Jeep is already lifted and already has 35’s, then deeper gears can only be an improvement to what you are currently getting.

Some people think of it strictly by rpm’s but that is incorrect.

I don’t think we are supposed to post links anymore on this forum for some reason even though that used to not be the case.

I use a site called 4LO which has several calculators and makes it easier to make a decision.
 

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When I had 33's on 4.10's in my 2007 it wasn't too bad. I never felt like I had issues but when I moved to 35's it was not fun to drive. I went to 5.13's and life is good again, I average 15+mpg with 35" mud tires and the speed limit on the highway here is 70 so I am usually running at 75. If I drive slower mpg is better, obviously.
 
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