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Discussion Starter · #1 ·
Tired of racking my brain over this, with costs being what they are, I'm afraid of making choice A only to wish afterwards i should've done choice B. Ive read all the regearing threads, charts and calc (like the grimmjeeper site calc) enough to make my eyes bleed.

I have an 08 jku 'Manual' trans with 3.21 gears. Still has stock bumpers but i do want to add aftermarket front/rear bumpers, rock sliders (not for rock crawling purposes), winch.

It originally came with (when i bought it used) 245/75/16 tires an i avg about 17-18mpg. When i put 285/75/16 falken tires on it dropped to 14.x mpg. I'm not sure ill ever go to 35s as that will require more work to the front axle.

I can't decide between 4.10 or 4.56 gears. based on the grimjeeper calc, 4.10 seems to be the gear to go with based on rpms from 55-70. My jeep sees the highway every day so highway rpms are a concern.

As i stated earlier, I'm afraid of choosing one and when its all said n done, wish i had gone with the other either which way. My highways here do have various inclines throughout.

Hopefully I've provided enough information but if not then please let me know.
 

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I'm running duratracs in 33-12.5-15, which measure out under 32". I just went to 4.56 in my 2011 2 door with a 6 speed. It's nice to have 6th gear back. I'm running 2700-2800 at 70. First is pretty deep. I am thinking that I'll go 35's eventually, and was a little worried that I'd feel like this was too much gear for the 33's, but it's actually not bad at all.
 

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Discussion Starter · #3 ·
I'm running duratracs in 33-12.5-15, which measure out under 32". I just went to 4.56 in my 2011 2 door with a 6 speed. It's nice to have 6th gear back. I'm running 2700-2800 at 70. First is pretty deep. I am thinking that I'll go 35's eventually, and was a little worried that I'd feel like this was too much gear for the 33's, but it's actually not bad at all.
Thanks, thats good information
 

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Since you have been rolling on 3.21s you are you slightly subpar performance so the 4.10s will probably be good enough for you. However, the common consensus is that 4.56 is the best match.

Since fuel economy on the road is important to you then go with the 4.10s. It's just that it's not cheap to swap gears and it's a shame no to choose the gear ratio that brings out the best of your engine.
 

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3.8 engine and the heavier 4 door, with 33's.
Just go with the 4.56 Ratio and you will be good to go........:thumb:

Even though your current plans are not for 35's, sometimes plans change.
So if they change, you won't have to re-gear a second time!!!!!!!!!
 
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