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I have asked several people and get different answers from everyone. Im new to this so please explain your answers as if your teaching your child something.

I just bought a 2013 Jeep Wrangler Sport JK-manual transmission-3.73 gear ratio
(Not sure if it matters...soft top/stock everything for now)

I plan to get a 2.5-3 inch spring lift, 35 inch tires and 17 inch wheels. I will do light traid riding but mostly daily driving.

Do I need to regear? What are the pro/cons if I do/dont?

Thanks for helping me with my new addiction ;-)
 

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I AM THERE4 I JEEP
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Put 35s on and see if you want to re-gear.
 

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Discussion Starter #5
Ok...I am VERY new to this and know nothing about cars. I am eager to learn though.

That being said, what am I looking for when I drive it after putting 35s on it? What will regearing it do for me?
 

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Ok...I am VERY new to this and know nothing about cars. I am eager to learn though.

That being said, what am I looking for when I drive it after putting 35s on it? What will regearing it do for me?
Just drive it stock for awhile and learn what it can do "as is".....especially if you don't know a lot about cars and Wranglers. What is the rush on the lift and 35's?
 

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Exactly, drive it and see. Vehicle performance is subjective to the driver.


The reason people tell you you should regear is the math and/or their own experience. The math says you need lower gears. That means a 3.6 liter Jeep with a manual transmission and 35" tires will be just below the standard range of performance expectations / or in another way, the expectations the manufacturer designed in to the vehicle. I think taller gears (3.21 stock) were chosen for MPG and modern customer expectations, as in that was a design expectation.

In effect, 35" on 3.73 would put you somewhere around the behavior of a Wrangler on 29" tires and 3.21 gears, (if you did the math, it would be somewhere just under 3.21:1, depending on the actual diameter of your 35" tires). At 70MPH, you would be at 1999 RPM in 6th gear (assuming you don't add significantly more rolling resistance or weight).

A gear chart is here and there are others elsewhere. They are all pretty-much the same. Scroll down to your year and transmission. Also remember that lots of 35" tires are closer to 34" on the ground, mounted to the Jeep.

If you were a friend of mine and lived next door, I'd tell you the same thing. Drive it and see. Then think about a lift (for looks or off road prowess, I don't care either way) If the difference in performance are negligible to you, the money for a regear can be used towards other things.
 

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Light Trail Usage

IMO if you are only going to do light trails, why not save yourself some money and leave it stock or get a 2" lift and put 33's on it with 17 inch wheels. The later is what I did and I left the gears at 3.73. I have been on some moderate to difficult trails with it and haven't seen any problems. I get anywhere from 15.5 - 19.5 mpg depending on what I am doing. The gearing is nice for my daily driving as well.
 

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I have 3.73 gears in my 2013 with 315/70/17 Duratracs and am happy with it. Still has plenty of power. Not too sure on how a heavier 35" tire would affect it though.....
 

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IMO if you are only going to do light trails, why not save yourself some money and leave it stock or get a 2" lift and put 33's on it with 17 inch wheels. The later is what I did and I left the gears at 3.73. I have been on some moderate to difficult trails with it and haven't seen any problems. I get anywhere from 15.5 - 19.5 mpg depending on what I am doing. The gearing is nice for my daily driving as well.
This is what I'm doing except with the stock 10 A lift and KM2 (32") tires. Probably keeping the 3.73 gears also and save the $1,500 quoted to regear for other stuff that makes it look real prutty when I take my wife to the mall.
 

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Originally Posted by croce14 View Post
Alabamajeep, can you post a pic?

Sorry but I'm not sure how to lol. I have one in my Jeep's profile though.
His Jeep is bad ass. I see it going up and down the street quite a bit!

I too will move on up to 315s on 17" wheels once I'm done with my bumpers, winch, and probably some skids.

I think that tire runs right around 34 inches tall when it's mounted on the Jeep, but I've never chalk tested one.
 

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I have a 2012 JK sport with a 2.5" RK lift with 35" duratracs on 17" rims. Let me tll you that around town the gearing is not bad. At highway speed if you have to go up a slight incline its a dog. I have he 3.21 gears so I will be regearing when I can afford. I'm sure the 3.73 will b better. I plan on going to 4.88 I think. We will see. After spending all that money on tires ,lift, and rims there's no money left in the kitty. Hmmmmm. Wht the going rate for a couple of kids. Lol. Just kidding
 

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Here is the reason people re gear. When we install larger tires, it takes more power to turn them, meaning it feels like your pulling a trailer, kinda sluggish. So what happens is we run the size tires we want, be it 33,35,37 and some have 40's. The larger the tire size, the lower the gear ratio you SHOULD install to make the jeep fell like it has stock tires on it.

Now note I said should, there are plenty of people who leave their stock gears in and add larger tires. If you have 3.73 and are adding 33's, there is no big deal, you should not feel too much power loss,

But add 37's and keep your stock 3.73's, and you will notice a power loss like I explained, (like towing a trailer)
With the 3.73 gear ratio and 35's, you might not need to re gear, Others who have this set up will chime in, You might find it bearable, meaning you might not notice too much of a difference.

I suggest you drive your jeep around some on the stock tires, see how it performs, check the gas mileage. Then install your tires, and compare the performance. If its something you can live with, great, you just saved 1500 bucks, if not, 4.10 should be perfect for you.

I hope that helps explain things better.
 

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Sorry but I'm not sure how to lol. I have one in my Jeep's profile though.
Upload your pics to photo bucket then copy the "IMG" and drop it here. Really quick and easy.
 

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By adding larger tires you are effectively reducing mechanical advantage. The tire is, in effect, a lever. Increasing the size of the tire is effectively moving the fulcrum between the pavement and the output shaft of the motor in such a way as to reduce leverage.

I have a 13' JKUR auto with 2.5" TF lift, 35" Toyo MTR and 3.73 gears. It's fine offroad due to the 4:1 t-case but around town, it's a bit sluggish. It depends a bit on how and where you drive as well. Stop and go traffic is the worst case scenario for an over-geared vehicle, milage suffers pretty badly. I believe 4.56 gears would be ideal for my application.

I should add that my performance has improved. At 3600 miles it drives much better than it did at 1000 miles. I expect it should improve up to at least 5000.
 
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