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dubb77 06-25-2013 02:53 AM

33's or 35's? Do I need gears?
I'm looking to do a 2.5" lift and can't decide which tire size to go with. I like 35s but heard I would need to re gear. Then some say that's not true. Any advice here would be great. If I go 33s am I good stock? 2013 JKU sport


Oh yeah, does the fact that I have the newer type motor have anything to do with it?
And I'm pretty sure my ratio is 3.21

ohioviper 06-25-2013 03:15 AM

I am running 33" Duratracs with 3:21 gears on a 13 3.6 auto. No issues at all. 35" I would consider a gear change but some run them with stock gears. My next set of tires will be 35" but I am saving up for gears .

Rtone1583 06-25-2013 03:32 AM

If you do have 3.21 gears, in my opinion, 35's will be too much for them and you will take a noticable hit in driveability. 33's should be okay with those gears.

With that said, it really depends on how you plan to use your Jeep. Mainly street driving you will be okay with 35's but you will notice a difference in acceleration both from a stop and on the highway. Off road ability is going to take a big hit with 35's against 3.21 gears. Unfortunately it's going to be a subjective matter on your part and buying a set of 35's without certainty is a hell of an expensive subjectivity test. I wish I could give you a better answer on that part of it.

As far as the lift, if you plan to stay with 33's the 2.5" lift may be a little much as far as looks are concerned (another subjective item).

Below is a picture of mine when it was on 33" KM2's with a 2" Old Man Emu "heavy" lift kit. About the only thing you can tell from the pic is how much clearance I had between the tire and fender and you can see that the 33's look small (I didn't have a problem with the looks personally).

Another thing to keep in mind when going for bigger tires is that you may need spacers if you are running stock wheels.

dubb77 06-25-2013 12:42 PM

I'm not going to run stock rims, and I might just save the money for a extra couple months then just re gear all at the same time. Don't want to sacrifice mpg or power not to mention looks.

brianb 06-25-2013 12:56 PM

My wifes 13 jku is lifted 2.5" with 315x75x16 duratracs. Does fine on flat ground, hills it downshifts a lot. Performance wise it still runs great, I am going to re-gear sooner or later but it is Not a must. And we are hand calculating 16.5-17 mpg with the 3.21's

JeepHerz 06-25-2013 01:24 PM

Here you go:
Its a little old- but you'll find this question gets asked about 2-3 times a week- so the questions/answers are basically the same.
I get on about every 3.21 thread- its not scientific but I'd say about 60% of people that respond are not happy with 3.21s and 35s. Some aren't happy but either deal or plan to re-gear down the road. There are those who think its perfectly fine. Performance will be affected. It is a matter of whether or not it will be enough to bother you.
I re-geared to 4.56s from 3.21s. I now have 35s. Save yourself $$ and hassle- get 33s. They look fine with a 2.5" lift and you avoid driveshaft issues. If this is your DD 35s are just for looks- is the possibility of a re-gear at $1500 to $2000 worth it?
Was for me- but I rock crawl, have a 3.5" lift and am totally vain. 35s do look killer.

HK_Runner 06-25-2013 02:15 PM

I live near/in the mountains of Colorado at 6,000 ft. All wheeling is done much higher. I have a 2-door 2012. I just switched to 35s and while it is fine for city driving, I don't like it when climbing up the mountain highways. For me, the 4.10 is not adequate. It jumps down 2 or even 3 gears, depending on grade and speed. It does this too frequently. I'll switch in the winter months and do 4.56s. It should then feel close to stock- 4.10s with 32s. True 33s would be perfect with 4.10s.

Barmanvarn 06-25-2013 02:26 PM

No regear needed for 33s. 35s, highly likely.

OffRoadCam09 06-25-2013 02:28 PM

Have 35's on my rig on 3.21's an in my opinion its gotta plenty of power to move them with the new motor

derf 06-25-2013 02:35 PM

3.21 gears weren't enough for me to make use of 6th gear with the stock 32" tires. I finally gave up downshifting all the time and just ran in 5th gear on the highway. I got better mileage running in 5th than I ever got running in 6th.

You'll want to regear no matter which tire you choose. Can you live with 3.21's and 33's? Sure. But once you regear you'll wonder why you didn't do it sooner.

If you had 3.73's, you could run 33's without a regear.

If you go 35's, get 4.10s for mileage, 4.56 (or even 4.88) gears for performance.

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