37s too big for DD?

[CarbonSteel]

Can you expand on your comment abou the 2.5GC riding better than the 3.5GC. I don't know that I've every seen anyone mention this before. Are you saying the 2.5 rides smoother, or is it more in the handling? Thanks!

All of the above plus what @c20040215 said. The 3.5" is stiffer, more affected by wind (yeah, it's only 1", but makes a difference), less tolerance for driveshaft angle due to caster, etc. so it can wander a bit more. There was a marked difference between the two.

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[AVGeek99]

Thanks for all the responses.

So it sounds like 3.5 and 37s is the way to go. I honestly can't see going bigger than 37s, but I guess that's easy to say right now. For the time being I think my 7ft garage door may be the limiting factor going bigger than 37s.

For regearing I think I will go with 4.88s. I definitely will not stick with 4.10s. I had a JKUS that had stock 3.21s/35s. It was a dog, 6th gear was completely useless. When I went to 4.56s it was a completely different animal, much more enjoyable. Comparing 4:88s/37s to 4.10s/35s it looks like 6th gear on the 4:88s is identical to 5th gear on 4.10s, which would be great. Of course this is not taking tire weight into account, but there is only a 10lb/tire difference in the STT Pros so that shouldn't make a super big difference. 5:13s is an intriguing option. If I was going to tow a lot or so a bunch of overlanding then I might think seriously about that. 5:13 would also be an enabler to go beyond 37s, which I don't want to do. Yes I know, yet.

About the tires. I know that MTs are supposed to be much better off road and not very good on. I've been running 35" STT Pros for the last 4 years, 2 years on my old JK and now 2 years on my JL. I only have experience with STT Pros so maybe a bit limited, but honestly I don't understand all the negative hype with MTs. The only realy negative I've experienced with the STT Pros is they definitely get louder as they wear. As far as performance goes, I've not had a single issue in wet or snowy/icy conditions. In fact they perform much better than the virtually brand new Tera Grapplers my JK had on when I bought it. That thing wasn't great on wet roads and was squirly as hell in snow and ice, even with 4WD engaged. Plus I got stuck the one time I went mudding with it, thankfully I had a winch. They don't ride the greatest with 40psi, but at 30psi they are very smooth. I'm kind of wondering with the extra sidewall and D load rating with the 37s if they will be smoother. I'm fine either way.

 

[bumpit]

Really depends on your appetite to wear out large mud tires for daily driving. You'll replace stuff like ball-joints and rod ends faster but it's not horrible and def something you'd end up doing down the line anyway. Mine isn't a daily but it could easily be one if I needed it to. I ran load range D 37s when I had them on the JL and it was just fine.

As far as getting louder as they wear down in my experience thats just a MT thing as I've had other brands also do that. MT aren't the same as they use to be and some of them are actually decent on road anymore for what it is imo.

 

[zouch]

37s work fine for a Daily for me.
(disclaimer; unlike the OP, i have the Diesel with the Automatic.)

of course i re-geared and upgraded all the steering to manage the additional rotating weight, and have no problems with it aside from the tiniest bit of rubbing at the rear lower portion of the fender liner on the Right Rear. (some judicious relocating of plastic makes it almost perfect.)

WRT tires; i went from 35" Mickey Baja Boss MTs to 37" BFG KM3s. i can't wait to have an excuse to go back to a set of Mickeys again.

 

[roaniecowpony]

All of the above plus what @c20040215 said. The 3.5" is stiffer, more affected by wind (yeah, it's only 1", but makes a difference), less tolerance for driveshaft angle due to caster, etc. so it can wander a bit more. There was a marked difference between the two.

The track bar and drag link angle is also steeper with the 3.5" MC GC. This causes more bump steer from the less than ideal angle of the draglink and lateral movement from the track bar. I feel the lateral movement when hitting bumps with my 3.5" MC GC. That is probably more annoying to me than a stiff ride.

 

[Zandcwhite]

Our 2022 XR rides better than stock on 3.5" metal cloak springs. Adding front control arm drop brackets put the control arms flatter than they were on a stock XR. We also added the yeti drag link flip and track bar bracket so the steering links are at roughly the same angle as a stock height Rubicon/better than the XR stock. To flip the drag link you will have to add about 1" more bump stop than you need to clear 37s. I didn't mind giving up that 1" of uptravel and we've since gone to 39s so we need the clearance anyway. In my opinion the vast majority of driving/handling issues are suspension angle related and easily solved.

 

[Whaler27]

I thought it might help to show a picture of 37s* on a 2” Mopar lift -which nets closer to 3” than 2”.

 

[Whaler27]

There’s really not that much difference between 35s and 37s once you regear. I researched and talked to several people for a long time before I decided on 4.88s. If I towed, or hauled a lot of weight with my auto trans….I probably would have done 5.13s. It’s relatively flat here so the 4.88s and auto work perfectly for me…. I think the 4.88s would work fine for you with 6mt and 37s, given how you say you use it……

I’ll add that the OP could also delay the regear for a year or two if he needs to. There are LOTS of folks driving around with 37s and 410 gears. My JL was a lot more capable in that condition than my TJ was with 456s and 33s. It’s not optimized, but it would be fine for a couple years of commuting before the move west (with everybody else).

 

[Roky]

I’ll add that the OP could also delay the regear for a year or two if he needs to. There are LOTS of folks driving around with 37s and 410 gears. My JL was a lot more capable in that condition than my TJ was with 456s and 33s. It’s not optimized, but it would be fine for a couple years of commuting before the move west (with everybody else).

Yeah, of course he can wait, goes without saying, I didn’t see 8th gear for a couple years, thought I had a 7 speed trans…..My reply to OP was just answering his question….However, if it was me and I had a manual transmission I wouldn’t wait, that’s just my .02….

 

[Zandcwhite]

I’ll add that the OP could also delay the regear for a year or two if he needs to. There are LOTS of folks driving around with 37s and 410 gears. My JL was a lot more capable in that condition than my TJ was with 456s and 33s. It’s not optimized, but it would be fine for a couple years of commuting before the move west (with everybody else).

I'm 100% convinced the guys who think you can't possibly put bigger tires on a JL without a regear have definitely never driven a tj or jk with an automatic especially. They all want to look at charts and compare gear ratios to those Jeeps. The tj had a 2.74 1st Gear in the auto. Our 1st Gear is so low in comparison you'd have to run a 7.0 gear in a TJ to match a JL with 4.10s. Are 4.10s optimal for 37s? No, but in my opinion with our 1st Gear 4.56s would be and I damn sure wouldn't spend $3k to make that small a gear change. Our 2019 was definitely better on the freeway and highways on 37s and 4.10s than it was when we went to 5.38s. Out 2022 xr felt like it was geared too low from the factory at freeway speed with 35s and 4.56s. Now on 39s, it wouldn't hurt to have a little more gear, but it still pulls harder than any tj or jk I've ever driven regardless of gearing. If I were ordering 1 tons I'd probably go 4.88s if I were sticking with 39s, but again I'm not about to sirens the money on a minor gear change. The manual is a little more sensitive to gearing but it would still be liveable.

 

[CarbonSteel]

Our 2019 was definitely better on the freeway and highways on 37s and 4.10s than it was when we went to 5.38s.

You re-geared a 2.0T to 5.38 with 37s and wonder why drivability suffered?

 

[iddpaul]

I'm really interested in the thoughts of those who have 37s on the DD. Other than having to regear and a potential hit to gas mileage, what are the other negatives of moving up to 37s? If I go to 37s they will be 37x12.5
R17 Cooper STT Pros. I currently have 315/70 R17s STT Pros.
[/QUOTE]



Lot's of great comments, so another one!

I drive daily on 37's (about 30 miles) and it's perfect. Started with 35's and a 2.5" lift (lower COG and less issues with pinion/caster), then moved to 3.5", 37's and re-gear. There are some considerations with 37's, more rotational mass/weight and torsional stress/wear on the steering & drivetrain plus more tweaking for caster/pinion, and always issues with leveling. Unless you have a 1 in 1000 Jeep you're going to have to add spacers somewhere to level out your ride. (Not a big issue but still something else to deal with)

I have a 2020 JLUR/3.6/auto, 3.5" lift, 37's and 4:88's and as mentioned, it's perfect for where I live (20' above sea level and a road trip to any destination). If I were at higher elevations or could do more climbing I would have gone 5:13's. IMHO it's dependent upon your environment and intended use, for 35" tires either 4:56 (probably closest to factory settings) or 4:88"s. For 37" tires, either 4:88's or 5:13. I will say that if I had a MT then I would probably go with 5:13's instead of 4:88's (with a JLUR you're not going to see that much difference on the trails between them since you'll be in the lower range anyway, but on the road you may see/feel the difference).

On the tires, it's up to you. I've run both MT and aggressive AT's on the road, find what you like and stick with them especially if they balance and handle well. (Again your environment should dictate what you use, myself I'm super happy with Nitto Trail Grapplers)

As I mentioned, I started with a good lift where the kit (control arms, etc., etc.) allowed adjustments for either 2.5 or 3.5 springs. After going to 3.5" and getting all my adjustments set (caster at 6.2), I added a bunch of MC spacers to level my ride but had to add more due to settling and sometimes added weight. After doing this, I stopped the madness, went back to 2.5" springs, removed all spacers and added adjustable coil spacers (ACOS from JKS or King) to the front and back. These add an additional 1" before adjustments, so I was back at 3.5" (2.5" Springs + 1" ACOS) and now I can adjust very easliy for ride and I was able to remove all the spacers (less pieces less problems?).

 

[Jimbits78]

I daily drive 80-100 miles a day. I ran 37’s for 2 summers and am now down to 35’s. I wasn’t concerned about power or gearing as both felt fine. I wasn’t concerned about fuel economy or what gear my transmission was in as there wasn’t a noticeable difference between the 35’s and 37’s. What I did notice immediately with 37’s is my brakes went from feeling “good” to feeling “acceptable” my steering went from feeling “stock” to feeling “heavy” at low speeds.
While I loved the looks of 37’s better I decided for my needs and uses I didn’t like the trade offs.
I regret the downsize every day however I enjoy the driving experience more.

But everyone has different needs and wants.

Either way you will still be rolling around in a bad ass Jeep

 

[Zandcwhite]

You re-geared a 2.0T to 5.38 with 37s and wonder why drivability suffered?

It was 38s, but over-geared is over-geared. I know you disagree but I found 4.56s too low on the freeway for the 35s on our stock XR and it has a 3.6L. That's my opinion after 20k miles. In the roughly 1k miles since the 39s went on I'll go as far as to say that's a better match with the 4.56s than 35s were if you tend to run 80+mph on the freeway, especially out here where those downhill stretches can last for miles. Why spin 2500rpms with virtually no load when I can cruise at 2000rpms? If I need more rpms for the uphill stretches that are just as long I can downshift...7 times. One of those gears has got to get me the rpms needed to climb even the steepest grades. As far as drivability I find only 2 gears matter, 1st being low enough to take off effectively and the 2nd overdrive being high enough to really take the load off the engine by dropping rpms.

 

[CarbonSteel]

It was 38s, but over-geared is over-geared. I know you disagree but I found 4.56s too low on the freeway for the 35s on our stock XR and it has a 3.6L. That's my opinion after 20k miles. In the roughly 1k miles since the 39s went on I'll go as far as to say that's a better match with the 4.56s than 35s were if you tend to run 80+mph on the freeway, especially out here where those downhill stretched can last for miles. Why spin 2500rpms with virtually no load when I can cruise at 2000rpms? If I need more rpms for the uphill stretches that are just as long I can downshift...7 times. One of those gears has got to get me the rpms needed to climb even the steepest grades.

It's all about the tolerance and the use case. You would have been fine with 5.13s or 4.88s with the 39's on the 2.0T--especially with a ZF8.

You seem run your Jeep much faster than most on the highway so you need a higher gear to keep the RPMs where you like it--provided the engine can produce the torque needed. My 3.6L at 7K ASL would not and so I was either dragging out gear shifts or staying in lower gears for far too long.

No longer an issue for me now that I have an engine that can produce the torque needed. It was such a pleasure driving through Raton Pass up to COS and not having the transmission up and downshift countless times and flat-out struggle. The boost went up and down, but the transmission did not--problem solved (for me).

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