35's vs 37's?

[Stormtroopin]

If you can find a nice set of BFG ko2s in 37s I would highly recommend pulling the trigger. Light weight, run a little smaller than advertised so you won’t rub and there pretty easy on the wallet for a 37 inch tire.

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[Minty JL]

Agreed. And as someone that CAN set up differentials of all makes and models, and HAS done so for way more extreme applications than going .6 mph over some rocks, I can confirm it is subjective and application dependent.

It does make sense sometimes to re-gear when going to much bigger than stock tire sizes. But necessary? Of course not. Not always. There are apparently many folks that go with big tires and just drive the damn thing with no complaints.

BINGO brother.

I've regeared in high performance applications and I agree a regear on a Jeep can be beneficial w/o a doubt.........but needed????, no.

Plus $5k for a regear and front locker is 10% of the initial purchase price of my '23 JTM new. Will eventually do it, yes. I have 26k miles of no issues this far.

Again, all in opinion

 

[JTGuy]

I got dana Spicer 4.88 gears installed, F&R for a little under $2K. A pro shop that knows what they do.

 

[mtudb24]

I have 37s, and I regeared my gladiator to 4.88s with my own two hands. (Never doing that again) I made a thread about the install with my feedback. To this day, I got better mileage with my 4.10s I think, but realistically that doesn't make much sense and is likely the change in 37s (milestar to baja boss) You'll be perfectly fine with 4.10s, but 4Hi is where I noticed the biggest change.

Whether 35s or 37s, your stock ball joints will fail, likely immediately. My JK and JT both ate BJs. The stock steering has been great, but I also opted for the metal cloak steering box reinforcement. I like the 37s when I rock crawl, but I'd curious what the Jeep feels like with 35s on these gears.

The ball joints will fail immediately? That seems like a generic statement? I have over 50K miles on a 2021 Max tow with mopar lift and 35's and stock ball joints. No issues whatsoever. Drives and rides great.

 

[Gladiator85]

No lies or denial, its a matter of where and how you wheel.

Gears and tire size always a subjective topics...... so no one person is the authority here, to include yourself.....IMO, respectfully

It's your rig do as you see fit. If you like having an 8 speed that hardly sees 8th and lives in 7th and sometimes 6th gear be my guest. I'm speaking from experience as I have 37s with 5.13s. I get the same gas mileage with more power on tap for all conditions.

I'm not praying there is a flat elevation or no wind. Don't have to with my set up. Can run 75 to almost 80 and hold OD 99.9% of the time still getting 16 to almost 17 mpg. Your JT is hating life on the highway with 35s or 37s on mall crawler 3.73 or 4.10 gears.

 

[Heavy D]

I'm assuming you guys running 37's have all regeared?

Yes. Went with 4.56 because my original plan was for 35s but ended up going with 37s.
Admittedly 4.88 or 5.13 would be a better match for heavy 37s but mine works great just like it is.. It goes into 8th with ease and stays there on the highway.

 

[RickF]

It's your rig do as you see fit. If you like having an 8 speed that hardly sees 8th and lives in 7th and sometimes 6th gear be my guest. I'm speaking from experience as I have 37s with 5.13s. I get the same gas mileage with more power on tap for all conditions.

I'm not praying there is a flat elevation or no wind. Don't have to with my set up. Can run 75 to almost 80 and hold OD 99.9% of the time still getting 16 to almost 17 mpg. Your JT is hating life on the highway with 35s or 37s on mall crawler 3.73 or 4.10 gears.

I would agree with 37s on 4.10 gears being out of whack, and 37s on 3.73 gears being WAY out of whack, but my stock Rubi, which came with 4.10 gearing, does great on 35s--it shifts normally, staying in 8th on the highway, and offroading has been great, too.

 

[chr15m]

This is always a subjective dilemma. Anyone ever on the fence in regard to tire size and regearing should simply sit with themselves and consider how they feel about any loss of power, fuel economy or whether holding top gear is of any consequence.

With 35s on my JTM I am still able to achieve 20mpg on full highway trips, I see no change in the transmission behavior that warrants concern as well, as I live in a very hilly area in the gorge I already was used to not seeing 8th gear stock. On highway trips I still have no issue holding 8th and ultimately the only reason it seems to be challenged is due to the speedometer being slightly off. Regardless of the grade I can get it to 8th gear if I get the speed over 68ish, once there I can then return to 60 and still be in 8th.

This of course is all not an issue for me because I spent years driving Toyotas and I honestly believe 37s on my JTM will still feel better than 33s did on my Tacoma. I eventually got bold with my 2018 Taco with the manual and 4.30s, ran 34s and had to drop to 4th to keep speed on 6-7% grades through the southern Oregon passes. The JT will only on rare occasion hit 5th through the same area and yet return better economy and not feel gutless, with 35s.

Even if my JT drove like my old Tacoma I would be fine with that as it still wasn't that bad. I recommend everyone try out something like an old 60 or 80 series LC and get used to a 0-60 in like 12 seconds, lol. It might help some with perspective.

It seems a "cart ahead of the horse" to bank on needing a regear before or at the time of a tire swap. Even if done affordably, dropping 2-3k is a sizeable chunk of cash mainly for subjective enjoyment purposes. Run the 35s or 37s and then decide if it's really needed. There are a lot of Tacomas on 33s out there that'll spend their whole lives on stock gearing with drivers that don't even bat an eye.

 

[aqcjeepGlad]

To all you guys running 37s, did you go 12.5 or 13.5? I'm on 35s and ready to move to 37s, but trying to decide on the width I want. Two things I would do differently for any person out there wanting to make some decision/changes. I wish I would have gone 37s instead of 35s AND I wish I would have done the AEV 2 inch lift right away instead of waiting two years. I thought the look on 35s was good/great but with the AEV lift it is great/awesome AND 37s will do the same thing again I feel.

SO, back to the original question 12.5 or 13.5??? Thanks

 

[Nobody]

Just bought a 2021 Mojave Glad, It is sweet! I had a JKU Wrangler for 8 years and traded it about 20 months ago for Canyon. Just had to have a Jeep again. It came with 315's on it which look nice. Will have to replace by Spring probably. Just curious how folks feel about 37"s? They look great but long term? I am not real mechanically inclined so please keep it simple for me!!!!!

I have a rubicon diesel on 37’s. Going on 40k ish miles. They run great Yokohama geolander MT’s. Getting a little loud in the last 4k miles. But nothing crazy. Will get another set when due for replacement.
- 18-21 mpg loaded.

 

[Zachanadandy]

No lies or denial, its a matter of where and how you wheel.

Gears and tire size always a subjective topics...... so no one person is the authority here, to include yourself.....IMO, respectfully

It's not even where or how you wheel, it's math and that hurts their heads. Final drive ratio is all that matters. It's not a wide ratio 4 speed. It will downshift and give you the same gearing they have. Just got back from another 1200 mile road trip, across the mojave desert in a wind storm, cruise control set at 85mph. At times climbing hills in a heavy wind it would shift down to 5th, with 5.13s it would have shifted to 6th... and we'd have the same drive ratio and rpms and power output as a result. Hauling lumber out to our property, on a trailer, still cruising 60mph on a washboard dirt road. But it won't hold 8th gear up a hill so it must need a regear? "More power on tap" is a myth. If we were locked into 1 gear is technically true, but a downshift gives you the same mechanical advantage, happens...automatically in an automatic, and is free. If you want to know what 5.13s feel like in the freeway, downshift 1 gear. 7th with 4.10s is identical to 5.13s in 8th... you know math.

 

[Dougstdig]

I just saw on Discount tire last night that the Cooper STT Pro’s are on sale for $362.

 

[Heavy D]

To all you guys running 37s, did you go 12.5 or 13.5? I'm on 35s and ready to move to 37s, but trying to decide on the width I want. Two things I would do differently for any person out there wanting to make some decision/changes. I wish I would have gone 37s instead of 35s AND I wish I would have done the AEV 2 inch lift right away instead of waiting two years. I thought the look on 35s was good/great but with the AEV lift it is great/awesome AND 37s will do the same thing again I feel.

SO, back to the original question 12.5 or 13.5??? Thanks

I went 13.5 because I like a wide footprint

 

[KevinC]

Every thread regarding gearing will provide a lot of feedback based on personal experiences, something I assume the original poster wants. Everyone is going to have a different opinion.

23 JT Mojave / 4.10 / 37 BFG KO2 / 18mpg daily commute / 8th gear normal

Where I do see a negative degradation - 4 HI in sand. It can/will bog down more than stock configuration. Off Road + helps keep it in a power band I could not manually do with shifting. I concluded airing down a little more helps also.

 

[Bonanza]

The ball joints will fail immediately? That seems like a generic statement? I have over 50K miles on a 2021 Max tow with mopar lift and 35's and stock ball joints. No issues whatsoever. Drives and rides great.

Have you inspected them? I've had 2 JKs before this JT, and each Jeep's ball joints have failed under 20k miles. Upsized tires and actually wheeling will eat these ball joints in no time flat. If you're just cruising around on the roads, I'm sure it'll be fine, but the trails and kind of wheeling I do-- no chance.

If you told me you recently inspected them and they weren't both flopping around like a politican being asked a direct question, I'd be shocked.

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