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Discussion Starter · #1 ·
Hey Guys,
I have a 2015 Rubicon. Currently on 35X12.5X17 Wranger MT/R Tires. Love this tire. No Doubt.

I am contemplating whether I should make the big boy jump to 37s or stick with the same?

I have to get tires very very soon because I did not rotate the MT/R as I should have. I have about 43K Miles on them and now the ride feels weird & getting the infamous death wobble frequently. I know my tires are un-even.

I don't do serious Rock Crawling, More of trails, mud & intermediate style.

What are the Pros and Cons for going to 37"? I know fuel Mileage will be affected (but we drive a jeep...so...)

What other "changes" would you recommend to the vehicle if I do jump to 37s?

I am lifted 3.5". Upgraded Fenders etc etc.

Thanks in advance for your input.

Cheers
-VMR
 

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In the same boat as you - have 35s and eyeing 37s. I was going to pull the trigger last fall, but lost my job. My budget has given me many months to weigh the options. This is my current thoughts:

1. Been wheeling on the 35s for 4 years now and the only drive chain or steering issue I have had is a bent rear axle flange. Still have all the original steering components at 80K miles without any issues.

2. Everyone I know rolling on 37s has had to upgrade their steering. tie-rods at minimum. Haven't really kept track, but it seems that the ones with 37s also brake stuff. Is it the 37s or is their wheeling style? Or a combination of both?

3. Everyone keeps saying that it is only 1" more ground clearance. However the larger tire also rolls over stuff better. See it on the trails.

4. The jeep with 35s has conquered all the local trails, so 37s are not "needed". 37s will make them easier, but will they become boring? Which will "abuse" the jeep more - the extra strain of 37s, or pushing the 35s with more gas and sometimes momentum to get over the rocks?

5. Basically the jeep has been built with 37s in mind someday. Rubicon, 4:88 gears, welded c-gussets, chromalloy rear axles, currently upgrading the rear driveshaft.

6. With a 2.5" lift and the flat fenders, 35s leave a lot of wheel well. 37s will fit nicely. The front clearance is not an issue. However the 35s match the rear contour perfectly when fully flexed. Will the 37s rub? Will the bump-stops need extending sacrificing some up travel? If yes, how much and will the loss really matter?

7. As mentioned, the steering is still stock. The pump has developed a slight wine. Will 37s push it over the edge or is it on its way out already? With 37s I know all the steering will eventually need replacing, question is how soon and will I have the $$ at the time? It will need replacing with 35 at some point also.

8. I like the 4:88s with the 35s off road. They are a little low for the 75mph highway driving I do to and from work. 37s will bring the rpms down, but how about power in the rolling hills?

9. Reading all the comments here on the forum, 37s do open a can of worms for upgrades. But then again I see 37s on many jeeps.

Been debating this for about a year now. I came to the logical conclusion that I should probably sick with 35s, but in the end, I probably will do the 37s because - Jeep Life!
 

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Discussion Starter · #3 ·
You my good Sir have described everything that I've been thinking in regards to the 37s.

The dilemma continues... I might just have to pull the trigger and deal with the consequences... because JEEP LIFE!

-Cheers!
 

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Very popular question here on the forum lately. Bottom line, wear items will wear faster, tie rod ends, unit hubs, ball joints etc.. Upgrades to some of those parts will help. Adding C gussets will help, maybe even a front axle truss etc.. Certainly carry spare front shafts.

As for the why, its the weight, and the diameter of the tire.. think of it as using a larger breaker bar vs a shorter one.. even just a little longer provide more torque which in tern puts more stress on things.

But in the end if you know what to expect then go for it.
 

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You my good Sir have described everything that I've been thinking in regards to the 37s.

The dilemma continues... I might just have to pull the trigger and deal with the consequences... because JEEP LIFE!

-Cheers!
The struggle is real!
 

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I might just have to pull the trigger and deal with the consequences... because JEEP LIFE!

That’s the attitude!- And make sure the bank account has the bandwidth.
 

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Discussion Starter · #7 ·
Soooo.. I chickened out and bought the 35s today.

Same Good Year 35X12.5X17 Wranger MT/R Tires.

I think it was more logical for me to get the same, I only had to buy 3 tires and use the spare, Which was brand new as my 4th.

So, I added the Fox ATS Steering Stabilizer 2.0 (for the $$ I saved on the 4th tire). LOL

..But bottom line, Yes, I chickened out =(
 

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No shame in that. For most people 35's are the right choice. They probably would be the right choice for us, but I ain't always smart and went with 37's. It has been pretty expensive......
But it makes me happy.
 

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BFG 37 KM3s will be 36” rolling diameter which run with 5.13 and MT is a great spot to be.
 
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Calculated rolling size for the 37x12.5x17 is 35.44" based on BFGs posted Rev per mile number of 569. The 37x13.5x17 is 36.40"with a rev per mile of 554.
I calibrated my tires with GPS going 70MPH. Possible there could be a small error.
 
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Same issue with me. Im in the process of replacing my wheel and tires. I decided a few years ago I wanted Beadlocks.....SMFH. Problem is I dont NEED beadlocks and nobody will mess with them so Im going back to street wheels. Currently running 35s and want to go to 37s. Im afraid Ill regret NOT going with 37s at least this go round and I can always go back to 35s next time for whatever reason. Id like to wheel way more than I do but 4 kids and a full time job make scheduling free time events more rare than preferred. Im pretty sure Ill do 37s at least 1 time, but theres still some doubt as to whether I should or not....
 

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If you want to run 37's, build for them and run them. But they do take more money to properly run than 35's do. They place more load on the Jeep, the steering, the axles, the brakes, everything.
And things will wear out faster as well.
But they are cool. Not a big difference functionally, but cool.
 

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37" tires are the new 35".... just like being 50 years old is the new 40. JK :)


I went to 37's from 35's about 4 months ago. It does cost a lot more and takes a lot more work to get there. In my case this jeep will never be my main vehicle/ride, but more of my toy. It's my fun vehicle, my weekend vacation Jeep, my get away off-road Jeep.... it makes me happy!

It does roll over things a little easier. I can't image the guys on 40's... you're cheating...HaHa!
 

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If you want to run 37's, build for them and run them. But they do take more money to properly run than 35's do. They place more load on the Jeep, the steering, the axles, the brakes, everything.
And things will wear out faster as well.
But they are cool. Not a big difference functionally, but cool.
Ive already upgraded some of the steering components (Thanks to an accident) installed the Teraflex Big Brake Kit, still need to do Axles, been looking at the Carbon Offroad setup. Already replaced Ball Joints with Synergy so Ive been building up to it, just has taken me longer than expected, plus its hard to convince the wife that I NEED these upgrades :whistling:
 

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Ive already upgraded some of the steering components (Thanks to an accident) installed the Teraflex Big Brake Kit, still need to do Axles, been looking at the Carbon Offroad setup. Already replaced Ball Joints with Synergy so Ive been building up to it, just has taken me longer than expected, plus its hard to convince the wife that I NEED these upgrades :whistling:
I have Carbon Offroad rear axle shafts and RCV front axle shafts. I had an issue with the wheel studs on the Carbon Offroad axle shafts and called them up looking to find out what the part number was so I could buy them. The guy at Carbon Offroad sent me new wheel studs for free, and rushed the shipping. I was impressed with the customer service. FYI, I bought them through Jason @ Krawl Off Road. Also have a D44 front axle out of a Rubi as ours came with a D30. I would rather have an aftermarket D44, or maybe 60's. But that was beyond my budget.
I hope you have better luck with your Synergy ball joints than my sister in-law had. Maybe their new version is better. I have TeraFelx ball joints, would rather have Dynatrac or Rare Parts like my sister in-law now has.
I also have an aluminum tie rod, along with Dynatrac big brakes.
The main thing left to get is hydro assist. Sometimes when wheeling you just can't turn those big tires, especially when locked. The RCVs help, but it is still a challenge at times.
 

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I have Carbon Offroad rear axle shafts and RCV front axle shafts. I had an issue with the wheel studs on the Carbon Offroad axle shafts and called them up looking to find out what the part number was so I could buy them. The guy at Carbon Offroad sent me new wheel studs for free, and rushed the shipping. I was impressed with the customer service. FYI, I bought them through Jason @ Krawl Off Road. Also have a D44 front axle out of a Rubi as ours came with a D30. I would rather have an aftermarket D44, or maybe 60's. But that was beyond my budget.
I hope you have better luck with your Synergy ball joints than my sister in-law had. Maybe their new version is better. I have TeraFelx ball joints, would rather have Dynatrac or Rare Parts like my sister in-law now has.
I also have an aluminum tie rod, along with Dynatrac big brakes.
The main thing left to get is hydro assist. Sometimes when wheeling you just can't turn those big tires, especially when locked. The RCVs help, but it is still a challenge at times.

I have bought most everything from Jason @ Krawl. I replaced the Ball Joints a few years back so if its been upgraded since, I dont have those. So far, no issues. Have Teraflex everything else, lift, Tie Rod/Drag Link kit, Falcon Shocks. Still stock on Axles and Driveshafts and keep going back and forth on replacing my current 35s with new 35s or going to 37s. :banghead:
 

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My free 37" KM3's cost me a lot of money. Probably should have stuck with the 35's.

I already had an upgraded front axle (Core 44 with RCV axle shafts) and a big brake kit. If you don't have those, factor those into your total.

You will need heavy duty steering components, Tie Rod, Drag Link, power steering box and high flow power steering pump (add the ps cooler too).

You will go thru unit bearings and ball joints much faster.

I went beadlocks, you don't have to.

So I had to upgrade all my steering (about $2K new tie rod and drag link, lightly used PSC big bore pump and steering box), I installed beadlocks (about $500 (diy rings, steel wheels, beer and pizza to my welder friend), I bought the road hazard warranty from 4WP (covers trail damage) $350, $500 Revolution chromoly rear axle shafts. I'm actually under geared for 37's. I'm on 4.56, should be a minimum of 4.88 recommended is 5.13's so to actually finish the job right, add in another $1500. I recently had to replace my track bar and ball joints. That was another $800.

My advice? stay with the 35's unless you wheel in places where you need more clearance and traction.
 
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