37s too big for DD?

[AVGeek99]

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.

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[SadRobot]

Go 37s. If you go 35s you're going to end up with 37s eventually. I'm getting on average 18.5-19.5 mpg (4.88 gears, 6 speed MT)

Only downside to going 37s is that once you have them you're then going to want to go to 40s. Slippery slope.

 

[Pig-Pen]

just a guess but i would think you would go with a shorter gear with a manual trans. i have the 8AT on 37s and 4.88s are sufficient but i would think a manual would need more. like 5.13?

 

[AVGeek99]

4:88s on 37s is actually a little shorter than stock 4:10s on stock 33s, so 4:88s should be plenty. 5.13s would be better if you towed stuff frequently, but I don't tow anything.

 

[SadRobot]

just a guess but i would think you would go with a shorter gear with a manual trans. i have the 8AT on 37s and 4.88s are sufficient but i would think a manual would need more. like 5.13?

If it's mostly highway or flat driving 4.88s should be fine. That's what I have and it's fine for around here. When I drove up to Lake Tahoe I could definitely feel it struggle to climb up the mountain pass.

When I was on 35s and 4.88s I could drive up the grapevine in 6th gear. With the 37s I have to downshift to 5th or even 4th.

 

[2nd 392]

4:88s on 37s is actually a little shorter than stock 4:10s on stock 33s, so 4:88s should be plenty. 5.13s would be better if you towed stuff frequently, but I don't tow anything.

4”- Plus an extra almost 100 lbs of tires over stock the numbers don’t account for. I went one step more than the a little shorter numbers and glad I did, - gained a half step in performance. Worth considering for performance ?

 

[Jeepskate512]

The only downside is you're windshield wipers getting bogged down with all the panties women will throw your way lol. In all honesty, I don't mind 37s on my DD. I have over 60k on 37s and 4.88s. I find that it all works just fine. It's also nice pulling up to my friends jeeps and trucks at work and asking them if they're tires are flat, because I've never seen such small ones before. Like SadRobot said, once you get 37's you'll want 40's. You hit a bit of a wall. Either way, good luck with your decision.

 

[SnowDawg]

I ran 37’s as a daily for a couple years. Never regretted it. I was 3.5 lift with 5:13’s. It was perfect. I’d personally go AT tire for commuting though. You can still wheel Moab just fine with an AT.

 

[Zandcwhite]

The wife's daily drive is about the same as yours and she does it on 39s and metalcloak 3.5" lift. It's an XR si 4.56 gears and the auto. Never felt a need for deeper gears. MPGs went from 14.1 average on stock 35s and 3.5" lift to 13.1 on 39s. I'll gladly give up that 1 mpg for an extra 4" of tire but to each his own. We regeared the last one all the way to 5.38s on 38s and it was terrible on the freeway and didn't gain much around town. Go with your gut and don't hear too low on my experience. You still have plenty of crawl ratio on 4LO. The idea that you get some kind of advantage anywhere but initial takeoff is lost on me. That's what downshifting is for. 4.88s in 5th gear is the same as 5.38s in 6th and so on until you get to 1st gear. I guess if you do primarily stop and go driving and never drive freeway speeds there no harm in gearing too deep but I'd much rather be able to drive down from Tahoe at 80mph at under 2k rpms personally.

 

[Roky]

'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.

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……

 

[MOOG5050]

I went from 35s to 37s on my XR. 4.56 with the 2.0t. The drive quality for a DD did not change. Slightly lower MPGs. Bigger step up and in. I would do 37s again.

 

[Steph1]

Your Jeep and yourself will be much happier going to 37s and 4.88 than it is with 35s on stock gears.

 

[roaniecowpony]

I also don't see a problem commuting with 37s. But commuting with mud tires sucks. They eventually get noisy as hell and they suck in the rain. I really don't commute anymore, since I retired. But I still went with a AT, albeit an aggressive AT. On slickrock, I believe they grip better than mud tires, all other things being equal.
I'm running Mickey Thompson BB AT 12.50x37R17 tires and find they do very well on the highway. We are in Moab today and ran some trails yesterday. I went up some incredibly steep walls with barely a squeel.

 

[five9dak]

The wife's daily drive is about the same as yours and she does it on 39s and metalcloak 3.5" lift. It's an XR si 4.56 gears and the auto. Never felt a need for deeper gears. MPGs went from 14.1 average on stock 35s and 3.5" lift to 13.1 on 39s. I'll gladly give up that 1 mpg for an extra 4" of tire but to each his own. We regeared the last one all the way to 5.38s on 38s and it was terrible on the freeway and didn't gain much around town. Go with your gut and don't hear too low on my experience. You still have plenty of crawl ratio on 4LO. The idea that you get some kind of advantage anywhere but initial takeoff is lost on me. That's what downshifting is for. 4.88s in 5th gear is the same as 5.38s in 6th and so on until you get to 1st gear. I guess if you do primarily stop and go driving and never drive freeway speeds there no harm in gearing too deep but I'd much rather be able to drive down from Tahoe at 80mph at under 2k rpms personally.

Agreed, is silly to me to see people complaining about cruising in ONLY 7th gear, lol. I have vehicles with three speeds.

 

[Zandcwhite]

I also don't see a problem commuting with 37s. But commuting with mud tires sucks. They eventually get noisy as hell and they suck in the rain. I really don't commute anymore, since I retired. But I still went with a AT, albeit an aggressive AT. On slickrock, I believe they grip better than mud tires, all other things being equal.
I'm running Mickey Thompson BB AT 12.50x37R17 tires and find they do very well on the highway. We are in Moab today and ran some trails yesterday. I went up some incredibly steep walls with barely a squeel.

A racing slick will grip on slick rock though? Rating any tires grip by how it performs on dry slick rock is like rating a vehicles acceleration by driving it off top of the world, everything's fast in a free fall. If you never run loose dirt, mud, or deep snow then by all means an AT is as good or better than an MT. They are definitely better street tires.

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