"Do I REALLY need to re-gear for 37s?" - Yes. Yes you do.

[Muddyape]

So my experience has been this; bought the JTR 3.6 Auto with 35” Ridge Grapplers and didnt know any better. Switched to BFG KM3 37’s (35.8 for the Tazer) and didnt really feel like I had an issue but again 37’s running small. Now Im running 39” BFG KM3 (37.75 for tazer with speedo barely off 1 mph) and it was a DOG. Hung in second gear and never hit 8th on the highway, and 7th rarely. So I just went to 5.13. Truck doesnt hang up in 2nd and can hit 8th gear at like 43-45 mph. Runs better on 39 with 5.13 than when I was with 35’s and 4.10’s.

In New England where I am its kinda “hilly” and it would struggle when I would take the same route to go to a buddys house. I dont have the issue anymore. Truck goes through gears quicker and doesnt drop down as much if at all when going up and down rolling hills on the road. I went with complete axle swaps (D60’s) because I was getting rid of failure points (FAD) because i’m doing some traveling across country and next year to the Arctic Circle.

Robustness aside, if all I did was gears I would be very happy with the performance of my truck with the gear swap. Much more lively and fun to drive.

Cant tell people what they could/should be tolerant of but if its a long term investment then it would seem to be a logical step as far as the long game if you are going to stay on bigger rubber. To the point where I'm considering 40’s for the majority of my time and going over to 38’s when I go on the longer journeys.

Just my .02

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[MudderNuker]

It really depends on your starting gear ratio and how you use your Gladiator. Having 3.73 instead of 4.10 would make it more likely that you'd want to regear. If my JTR with 4.10 and 37's lived it's life down in Phoenix, at an elevation of 1200 feet, and never towed, then I probably wouldn't have regeared. Since my JTR is at our cabin at 6600 feet of elevation (where the normally aspirated 3.6L is down 20% in HP due to lower air density) and it's purpose in life is to tow our 3000 lb. trailer, I had it regeared with 5.13s.

We retired last year and decided to move to our cabin and sell our main home. Our cabin is at 7,300 feet in elevation. Going by the standard 3% for every 1,000, my JTR is down approximately 21.9% in HP. I went from 33" to 35" and lightweight wheels and didn't notice much difference. I still see 8th on flats like it was designed for. I am considering adding a Scorcher module to hopefully make up for some of the altitude loses and going to 35". For now I feel like 4.10 and auto is still adequate for 35", even at my altitude. Only while towing, I notice a difference. Our Geo Pro 19BH camper is 3,500 and I have no issues towing it. Now, when towing our tractor on the flat bed trailer, combined weight of around 6,000 ish, the JTR felt gutless.

 

[RK Racing]

My opinion………………. If you do not re-gear for 37’s or bigger……………. You are simply a cheap bastard. Now, if you want to be a cheap bastard on purpose that is your God-given, right. Party On!

 

[RubiNewbCB]

Yeah, autotradgic copes with it decently, so people say. Which is why I made sure to state my opinion with my transmission type, lol

Diesels though, they apparently dont give a flying F about 37's, lol

Diesels JTs are the "Honey Badgers" of Jeep combinations. They don't GAF about 37s, Lifts, or Rooftop Tents.

 

[RHINO79]

Geez, my Manual trans JTR on OEM 33" is slow as molasses. I couldnt imagine 37". Im probably going 5.38 to regain what I'd lose, and then get some extra rev into it. The 3.6 is quite gutless. Not that I've had anything else in the jeep line besides a couple 4.0 XJ's.

Agree 100% I test drove a manual and couldn't believe how anemic the power was.

 

[OldSarge]

I

Well, no you don't HAVE to re-gear when adding 37" tires to a 3.6 automatic JT, but you will want to. After 3.5 years on 35" Toyo AT IIIs, I switched to 37" Yokahama Geolander ATXs when Walmart forced me to with an unbelievably great deal. The 4:10 gear-ratio Jeep Mojave looks great and drives great on the 37s, but there is a noticeable lack of pep in the step now. The JT is a bit more sluggish off the start. I love the new stance and added clearance but will definitely be re-gearing to 4:88 to recover the lost pop and turn those larger tires.

100% agree - have 5.13s on my JT with 37s and it drives great

 

[mtoddsolomon]

Some of y'all must have been riving rocket ships before your Gladiator. I had went from a 2016 Yukon Denali with the 6.2L to a stock Rubicon and I felt like the 3.6 had a noticeable increase in pep. I've had several other Jeeps but compared to my TJ from college, this thing feels incredible.

I have the Patagonia X/T 37s on AEV Saltas and I barely noticed a difference from stock. I have no intention to re-gear and on the highway I'm still getting 19-20 MPG with cruise set at 65 (in a 60).

 

[Zachanadandy]

The idea that you'll gain power back by regearing is just false. 7th gear with 4.10s is identical to 8th gear with 5.13s and you can work your way down through the gears from there. Unless you feel like 1st gear isn't low enough, you aren't changing the final drive ratio which is all the engine sees as far as load. The transmission will just pick 1 gear lower for the same load...automatically. Why gear an 8 speed with 2 overdrives so low that it's in 8th gear by 43mph, half the speed limit? We ran 5.38s with 38s and it was terrible at speed. Always in 8th, revving high even downhill with a tailwind. 4.10s with 37s is far better and got better fuel economy. If you want more power, add a tune or forced induction. Otherwise you're just a downshift away from the same power you get from a regear.

 

[Roger2486]

I'm presently running at 2021 JTR set kited out / set up for overlanding, which is on the heavy side exceeding GVR 80 % of the time on 37's with factory 4:10's with a Taser . I never see 8th gear, routinely am in between 5-7 gear at 70-75mph. Hit a hill, wind or heat and she drops to 4th, etc. After long talks with my rear end guy between 5:13 or 5:38's for my application / use, having factory Dana / Spicer 5:38's being done next week. On 35's it was doable... 37's with the weight is too much.

 

[Vegas_Blue]

Yeah, autotradgic copes with it decently, so people say. Which is why I made sure to state my opinion with my transmission type, lol

Diesels though, they apparently dont give a flying F about 37's, lol

Based on my personal experience, you are correct about the diesel my friend.

 

[Badweather]

Recently went from stock 33” tires to 37” tires. Ran stock 4.10 gears for about 2 months and then regeared to 5.13 the Jeep is so much more fun to drive. First gear is over pretty quick but cruising on the highway is a pleasure in 8th gear and 70 mph.

 

[Gladi8r_22]

Truer words were never spoken!

I’m thinking 38s next time around or maybe some all terrain 40s

Copy that!! I'm running 38x13.5's Nitto Trail Grap. still with stock 3.73 gears, no issue from start, but very rare to get into 8th unless super flat. When I can get into 8th I'm doing about 78-80 mph @ 1700 RPMs.

Will be looking to go to 40's & regear to 4.56 at some point.

I do have a question though, why is it we always hear about people say they need to regear to get power back from going to a larger tire, but rarely hear talk about how to improve their braking from all the increased weight?

 

[Minty JL]

Needed - No
Desired - yes

I'm almost at 25,000 miles now on 37x13.5.......its not hateful, does surprisingly well.

 

[Zachanadandy]

Needed - No
Desired - yes

I'm almost at 25,000 miles now on 37x13.5.......its not hateful, does surprisingly well.

If regearing was free, I'd go to 4.56s. Locally regearing is $3k, absolutely not worth the cost.

 

[Minty JL]

If regearing was free, I'd go to 4.56s. Locally regearing is $3k, absolutely not worth the cost.

Yeah my last quote from the best shop in the area was like $3700 parts and labor.

Sooner or later.....probably after I pay it off early next year i will got with 5.13s and add a front locker. Buy once and cry once

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