37s too big for DD?

[Zandcwhite]

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).

It is hard to beat boost at altitude for sure. Odds are the next Jeep will be fully electric and altitude won't mean anything anymore.

Sponsored

 

[shikaka]

I'm going into a local shop this week to get on the schedule for a lift (MC Game Changer). I'm trying to decide between a 3.5 inch lift and moving up to 37s or a 2.5 inch lift and sticking with 35s. I know that 37s will require a regear and will go to 4:88s if I go that route. This is for my DD JLUR 6MT. I have about a 40 mile round trip commute each day.

I don't wheel much around home because the options are pretty limited but I do get to Moab once or twice a year and hopefully will be moving out west in the next few years.

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.

I ran my auto 2010 JKU for 8yrs as a daily driver with 37s (Heavy Toyo MTs 37x13.5 R17 and aftermarket wheels) w/5.13 gears. Had installed a 2.5in Teraflex kit along with a 3/4inch body lift to fit the 37s. Towed several times and drove to Chicago from Dallas twice, however I highly recommend some proper length drive shafts after the lift because they will break and it's not fun. C gussets and a heavy duty track bar were crucial for the front to help strengthen the dana 35 and help with handling (much less body roll). Taller bump stops help with rubbing/bottoming out in the rear end. I would go with the 13.5 width tires just because they look so much meaner, obviously make sure to get the proper wheel offset so they don't rub. All in all it was fun and very doable. I still have my jeep with the exact same setup but it's now being used for enjoying the weather with the top/doors off and for local driving only. Good luck!

 

[AVGeek99]

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.

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).

My desire to regear is based on my experience with my 6MT 2012 JKUS. When I got that it had 35s with the stock 3.21 gears. It was a dog, a fat lazy one at that. I learned very quickly that 6th gear was useless to say the least. I actually drove it like that for 2 years. It took a trip to Duluth, MN to realize how bad 1st gear. On the flats it was fine, but in Duluth there were streets where I could bearly get going 1st gear. After 2 years I regeared to 4.56s and it was like a new jeep. 1st gear was no longer a problem and I could cruize down the highway at 80+.

When I got my 6MT JLUR I was a little apprehensive about running 35's on the stock 4.10s. I wasn't so worried about 1st gear because it is much than 1st in the JK, but I was worried about making 6th gear useless on the highway. My jitters were very quickly calmed as the JL does very well with 35s on the 4.10s. Although it doesn't take a lot of incline to start losing speed in 6th.

My only complaint with this set up is hilly (not mountains) areas. On my way to CO and UT I drive through Northeast Nebraska (HA! NE NE), which is hilly as hell. Who knew? It's just constant up and down. 6th gear doesn't come close to holding speed and 5th sometimes struggles, so I'm just constantly shifting, it's litterally worse than stop and go traffic. With 37s on 4.10s in that terrain 6th would be useless so it would be between 5th and 4th. I don't mind so much having to downshift in the mountains, becuase it's not constant shifting.

Ratio wise 6th gear with 4.88s/37s is identical to 4.10s with 35s. In my experience that should work very well. Going to 5.13s I think would be too short. Without towing or being weighted down with overlanding gear, I think I would want one more gear on the highway. Plus 5.13s would be a gateway to bigger tires, and I really don't want to ever go bigger than 37s, I'm not tall enough.

 

[SadRobot]

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.

I'm also envious of anyone with a tall garage door. I'm at my limit with my lift and 37s on my garage. I had to remove my old trolley style garage door opener and install a jackshaft style one just to be able to get my Jeep to fit into it.

 

[JINO]

For me it's fine. Getting in and out isn't as easy as it was stock haha.
Luckily I have the 3.0t, so didn't need to change my gearing, still on stock 3.73 and getting 25 mpg withba roofrack.
520 lbs of tq makes passing on the highway easy and fun.
My wife has to jump to get in lol

 

[Whaler27]

My desire to regear is based on my experience with my 6MT 2012 JKUS. When I got that it had 35s with the stock 3.21 gears. It was a dog, a fat lazy one at that. I learned very quickly that 6th gear was useless to say the least. I actually drove it like that for 2 years. It took a trip to Duluth, MN to realize how bad 1st gear. On the flats it was fine, but in Duluth there were streets where I could bearly get going 1st gear. After 2 years I regeared to 4.56s and it was like a new jeep. 1st gear was no longer a problem and I could cruize down the highway at 80+.

When I got my 6MT JLUR I was a little apprehensive about running 35's on the stock 4.10s. I wasn't so worried about 1st gear because it is much than 1st in the JK, but I was worried about making 6th gear useless on the highway. My jitters were very quickly calmed as the JL does very well with 35s on the 4.10s. Although it doesn't take a lot of incline to start losing speed in 6th.

My only complaint with this set up is hilly (not mountains) areas. On my way to CO and UT I drive through Northeast Nebraska (HA! NE NE), which is hilly as hell. Who knew? It's just constant up and down. 6th gear doesn't come close to holding speed and 5th sometimes struggles, so I'm just constantly shifting, it's litterally worse than stop and go traffic. With 37s on 4.10s in that terrain 6th would be useless so it would be between 5th and 4th. I don't mind so much having to downshift in the mountains, becuase it's not constant shifting.

Ratio wise 6th gear with 4.88s/37s is identical to 4.10s with 35s. In my experience that should work very well. Going to 5.13s I think would be too short. Without towing or being weighted down with overlanding gear, I think I would want one more gear on the highway. Plus 5.13s would be a gateway to bigger tires, and I really don't want to ever go bigger than 37s, I'm not tall enough.

Nobody is arguing against a regear. I’m in favor of it. But the JL isn’t a TJ, or a JK, so there’s less urgency for a regear, especially for a flat-landing commuter. It won’t be a hotrod, but it won’t be your JK either.

I live in Oregon. Our hills are bigger than those in Nebraska — by an order of magnitude — Nebraska seems flat to me — and I had no trouble traversing the Cascades prior to my regear. I wasn’t seeing much of 7th or 8th gear, so my gearing wasn’t optimized, but it worked fine until I had the time and money to regear.

The gearing charts are a smart place to start, but there is more to the equation as tire and wheel weight increase with increasing rolling resistance. If you read the MANY posts on “488 or 513” here and elsewhere you’ll see vigorous debate with plenty of good points on both sides. In the end it’s a matter of balancing costs, and benefits, and personal preferences. For me, 488s are perfect most of the time, but I do almost no rock crawling and my overlanding is infrequent. If I did much more of either 513s would be the clear choice.

 

[Zandcwhite]

I think the issue is exacerbated with the manual as the driver is constantly aware of the need to downshift. Even the 6 speed is a double overdrive transmission. 4th gear is 1-1. Of course you'll have to shift out of 6th on the slightest hill or heavy wind, even 5th is still an overdrive gear. It's like the guys complaining about the 8 speed not holding 8th under those conditions. In my opinion it shouldn't. That's the point of a double overdrive. You have the 1st overdrive for normal driving and the 2nd one to really drop the rpms for light loads. A stock sport with 3.45 gears and 32" tires is turning just 2060rpm at 85mph in 8th gear. Even my XR on 39s and stock 4.56 gears is geared deeper and turning 2240rpm at the same speed. If you listen to the guys on here I should be running at least 5.13 gears for 39s, putting that no load freeway rpm up at 2520, why? Because it will downshift into 7th in heavy head winds or slight inclines? Because it will down shift all the way into 4th pulling a steep grade? That's what it should do. Taking a 6 or 8 speed double overdrive transmission and gearing the axles so deep it can cruise around in top gear in even moderate to heavy loads defeats the purpose of all that gearing in my opinion. Our 2019 on 38s with 5.38 gears was literally in 8th gear by about 45mph and of course it would hold 8th on pretty steep inclines. The problem is it wouldn't upshift to get the rpms below 2700rpm at 85mph even coming down the 20mile long, straight, downhill section of freeway between Vegas and Baker,CA. I'd much rather see 2200rpm in those conditions as increasing the rpm on the uphill sections is easily handled by 7 other gears built right in to the trans.

 

[AVGeek99]

Agreed that a regear is not as necessary or urgently needed with an automatic. But with a manual the 6spd can quickly turn into a 5spd and that's what I want to avoid. 4.88 is as short as I'll go. Any shorter and you defeat the purpose of having 2 OD gears as @Zandcwhite explains. 4.88s with 37s is also very close to stock Rubi ratios with 4.10s and stock tires. It's a little bit shorter to handle the extra weight and resistance of the lift. I really liked the stock configuration for the 2 weeks I drove it like that.

 

[AVGeek99]

Ok switching things up a bit. I went into the shop today and got on the schedule. I got in for the week of the 30th. I am going with the GC and a 4:88 regear. I'm going hold off on the tires until I need new ones and I will move up to 37s at that time. I want to get the big ticket items out of the way now. New tires will be a necessity by next spring so I'll just wait until then.

After talking to the guy at the shop I went with a 2.5GC instead of the 3.5. I was mulling over the 2.5 v 3.5 ever since I got my JLUR long time and had basically convinced myself to go with the 3.5. I knew a Rubi would could do 37s with a 2.5" lift, but required more bump stop that reduces the up travel. The guy at the shop said that MC was a bit conservative with their lift measurements and since my build won't be super heavy I'll likely get 3" out of the 2.5, and more like 4" with the 3.5. There's no difference in cost between the 2.5 and 3.5 and I can change it in the next couple days if I want. If I go witht he 3.5 I'll get the rear drop brackets so that would add the cost of those.

So my new question... From an off road capability perspective only, how much am I giving up by going with 2.5 and 37s vs 3.5 and 37s?

 

[iddpaul]

The Rubi can easily do 37's with 2.5". Depending on what you're doing and where you go, with the 2.5" really giving you 3" and correct bump stops/shock extension, you should be fine and I don't think you're giving up much. This will also keep your COG lower, give you better road manners and maybe less wind resistance on the road and hopefully make your pinion/caster corrections better (less vibration). Remember you will get some settling (spring dependent) over time. When I had my 2.5" with 37's it was perfect on the road and light trails but I did rub in the wells on the rear at full compression (EVO 2.5 kit with Kings). I am carrying some weight so I changed bump stops and went to 3.5" (ACOS so I could easily adjust in the future) and have had no issues since (looking at my rig, I do sit a little high but I like that).

 

[Gorilla57]

I’m on 37’s with beadlocks, 4” lift, heavy rig, 3.6L and love my new 5.13’s that replaced 4.88’s. I don’t drive 85mph in this, but do cruise at 75-80. The rig really drives nice now with the 5.13 and still does downshift as needed. I felt the rig with stock 33’s and 4.10’s downshifted way too much. That’s why I went 4.88’s originally as 37’s and 4.59 theoretical gears would be the same as stock. With all the extra weight and lift, the 4.88’s and 37’s downshifted just like a stock setup. Now it downshifts only 1 gear vs 2 or 3 to maintain speeds up the steep interstates hills around here. Just my 2 cents.

 

[pfletcher229648]

You do you, if you like the look of 37's on a DD then go for it, MPG be damned. I like the all around drive and comfort and look of my JLUR XR on 35's. I can get into my Wrangler by slightly elevating my right butt cheek and sliding in, no running boards needed, 37's might cause me to have to jump slightly to get into my jeep as I have gotten used to not using running boards to step up.

As a side note, and I leave it up to you to determine my motivation, my wife likes the Wrangler with 35's and I like my wife, so there's that.

 

[AVGeek99]

I'm only about 5'8". In my stock Rubi (on 35s) I can get in how you describe getting into your XR on 35s. I have taken my ability to get in into consideration when choosing a lift height. My JK was lifted a decent amount higer than my stock JL.

My JK was a Sahara so it had the step bar (far superior to the running boards JL Sports and Saharas have, IMO) but it felt very awkward using it to get in. I quickly learned to grab the steering wheel, step in with my right foot and push off with my left and pull myself in using the steering wheel.

When my JL is lifted it'll be similar in height or a little higher than my JK. The same technique should work just fine. I loath running boards and steps. They just hang lower and reduce ground clearance. But I do understand why some people have them.

 

[gbr]

I'm currently running 38" Milestar Patagonia tires as my DD (excellent when new, not so much after 31K miles). I'm moving to 39" K02s because I loved my 35" K02s on my old JK. In reality, the K02 is only 1/2" taller, but it is 4 pounds lighter.

I wheeled my 38s pretty good (Moab, local Canadian Shield stuff) on 4.10 and 4.88 with no issues. I'm looking at going 5.13. My mileage is okay. Any head wind and I might as well have a leak in my tank, though.

 

[AVGeek99]

I changed my mind again. The question of 2.5 vs 3.5 was eating at me ever since I left the Shop on Thursday. I started thinking "buy once, cry once". I know in the grand scheme of things it wouldn't cost all that much to swap out 3.5 springs but then if I just go with 3.5 now there's no extra cost. Well I did add the DB3 drop link option to level out he RCAs so there's a little cost there. Sales manager at the shop confirmed all of my order today with the 3.5. Goes in the week of the 30th. I can't wait!!!

Sponsored