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Who Is Running 37's on their JKU? I have questions

Discussion in 'Wrangler JK (2007-2017)' started by Jdubya420, Jul 1, 2019.

  1. Jul 1, 2019 at 6:06 PM
    #1
    Jdubya420

    Jdubya420 [OP] Member

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    First off, hello, I am a newbie to the forum and jeeps in general, though I am wondering now why I never bought one of these earlier in my life...

    I have a 2017 JKU and I am considering running 37" tall tires. I know that I will have to re-gear and i will have to upgrade the brakes to stop the thing. My question is, will upgrading to a drilled and slotted rotor and heavy duty pad suffice or will I need to add a big brake kit? Any help or insight you guys can provide would be helpful...
     
  2. Jul 1, 2019 at 6:33 PM
    #2
    JKBob 25

    JKBob 25 Well-Known Member

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    Welcome to the forum @Jdubya420 .
    Sorry, I can't help with your question. But I know there's several members here that are running simiular set ups, that could help. @OFFGRID @The4x4Guys . Are 2 that come to mind.
    Personally, I'm running 35s with stock brakes. And no issues. But I know running more rubber can create other issues.
    I look forward to what others have to say since eventually. I'd like to upgrade to 37s.
     
    The4x4Guys and Jdubya420 [OP] like this.
  3. Jul 1, 2019 at 7:04 PM
    #3
    aggrex

    aggrex Well-Known Member

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    Drilled/slotted rotor could be an upgrade but the big brake kits use a larger diameter rotor with matching calipers/pads that increase braking performance. Some kits recommend upgrading the booster+MC.
     
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  4. Jul 1, 2019 at 7:20 PM
    #4
    JKBob 25

    JKBob 25 Well-Known Member

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    Oh yeah.....we also have @aggrex. He pretty much knows his shit also too. :boink::coffee:
     
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  5. Jul 1, 2019 at 8:04 PM
    #5
    The4x4Guys

    The4x4Guys Well-Known Member

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    Mopar 2" lift, 37" BFG KO2's, KMC Rockstar 17" wheels, JCR Offroad front and rear bumpers, WARN Zeon 10-S, CoolTech CB Radio Kit, Rock Slide Engineering step sliders, TeraFlex adjustable steering stabilizer, Rock Krawler adjustable track bars,Magnaflow dual tip black exhaust.
    I have a 2018 JLUR with 37's but I'm not certain that a JK to JL comparison would be 100% accurate. Bu here is my opinion, I will leave facts to guys who either know better or have done it. When I had a 2015 JKUR running 35's I had to get a 2" Mopar lift to handle the tires. Stopping was a non-issue for me. To run 37's the JKUR would have needed a far more substantial lift to allow the tires to clear without rubbing. So my experience is that a JK can run 33's with no lift, 35's with a 2" lift, and 37's with 4"+, re-gearing is likely to be more important with 37's. If you decide to look into the larger brakes, I'd highly recommend you look at the Teraflex big brake kit for the JK but they are pricey and may not be necessary.

    On the JL, you can run 35's right off the showroom floor, but to run 37's I had to do a 2" lift. So far re-gearing has not been an issue with the 4.10 Rubi setup and stopping is still a non-issue.

    Before I'd spent the big bucks on brakes, I'd take care of the lift, re-gearing, wheels and tires - that ought to set your pocketbook back a bit.

    PM and I can can get you quotes on any/all upgrades from our online store The 4x4 Guys .com (leave out the blanks)

    Bob
     
    Last edited: Jul 1, 2019
    JKBob 25 and aggrex like this.
  6. Jul 1, 2019 at 8:11 PM
    #6
    The4x4Guys

    The4x4Guys Well-Known Member

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    Mopar 2" lift, 37" BFG KO2's, KMC Rockstar 17" wheels, JCR Offroad front and rear bumpers, WARN Zeon 10-S, CoolTech CB Radio Kit, Rock Slide Engineering step sliders, TeraFlex adjustable steering stabilizer, Rock Krawler adjustable track bars,Magnaflow dual tip black exhaust.
    Oh and @aggrex is absolutely correct about the larger rotor, the kits I've seen do indeed suggest that you upgrade the booster and master cylinder. Which makes for a fairly expensive upgrade. I would do it, if I found the stopping distance issue to require it, but not before that.
     
    JKBob 25 likes this.
  7. Jul 2, 2019 at 7:00 AM
    #7
    Blue Baby Sound

    Blue Baby Sound Well-Known Member

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    Build threads in sig
    We've run stock 32s, 35s, a couple of different 37s and 40s on our JKs. IMO the stock brakes are OK up to a 35" tire, past that a big rotor kit or big brake kit should be installed.

    I'm personally not a fan of drilled and/or slotted rotors on a Jeep. I've run them before and they just seem to trap dust and dirt and squeal when on the trail. If you're street only then they'd probably be OK.

    Now whenever someone is making a decision on tire size I want to make sure they know what they're getting into.
    We've been able to run a light 35 with limited increase in wear/tear on components.
    Anytime we've made the jump to 37s wear/tear greatly increases. So make sure if you go 37s that you're budgeting for components that fail. Stuff like ball joints, tie rod ends, drag link end, axle shafts, unit bearings (hub assembly), etc. For us it all started fairly soon after the upgrade, rear axle shafts went first, then ball joints, then unit bearings (and they keep going out), then drag link/tie rod. All within 40k miles.

    So unless you really need the extra 1" of ground clearance of a 37 over a 35, then I always suggest sticking with a 35.

    Good luck!!
     
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  8. Jul 2, 2019 at 5:57 PM
    #8
    Jdubya420

    Jdubya420 [OP] Member

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    That is the problem, I feel like every time I turn around I need something else to make 37s work on this thing. First it was the regear, then the spare tire mount, then flat fenders, now its brakes... I am starting to get overwhelmed. I wanted to just make upgrades as I go but now I am stock piling parts in my garage because I don't want to tear the thing up.

    I purchased an EVO Enforcer 3" lift, and according to Evo you can run 37s with flat fenders.

    I don't really need the 1" of ground clearance but I like the look of 37s on a JKU with a 17" rim. I am not a big fan of the large wheel/small tire look. It is hard to gauge what a 35 on a 17 will look like, most of the photos I see are 37" tires.
     
  9. Jul 2, 2019 at 6:14 PM
    #9
    aggrex

    aggrex Well-Known Member

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    JKBob 25 likes this.
  10. Jul 2, 2019 at 6:18 PM
    #10
    The4x4Guys

    The4x4Guys Well-Known Member

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    When I had my 2015 JKUR (I miss it), I had a 2" Mopar lift and 35" Fuel tires. It looked great and the stance was perfect.

    While I have 37's on my JLUR, that is not an apple to apple comparison. I personally think the 35's are the perfect tire size for a JK, while 37's for a JL are acceptable.IMG_0096.jpg IMG_0098.jpg IMG_0099.jpg
     
  11. Jul 2, 2019 at 6:22 PM
    #11
    Jdubya420

    Jdubya420 [OP] Member

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    What diameter wheel is this?
     
  12. Jul 2, 2019 at 6:24 PM
    #12
    The4x4Guys

    The4x4Guys Well-Known Member

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    There are 17" wheels

    Tires were 35 x 12.5
     
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  13. Jul 2, 2019 at 6:27 PM
    #13
    The4x4Guys

    The4x4Guys Well-Known Member

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    This was great ride, nice height, good lift kit, and tires were relatively quiet. If I had to do it all over I would have bought the BFG KO2's (which I have now on both a 2108 JLUR and a 2003 TJ)
     
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  14. Jul 2, 2019 at 6:28 PM
    #14
    The4x4Guys

    The4x4Guys Well-Known Member

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    What all have you purchased so far?
     
  15. Jul 2, 2019 at 6:50 PM
    #15
    Jdubya420

    Jdubya420 [OP] Member

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    Evo Enforcer Stage 3 Lift. Fox 2.0 Shocks and 17" Method model 301.

    I really like the look of this, but I would like to get the thing lifted and put the wheels on and add/replace parts as I go. I a cool with the cost of the regear, I would like to hold off on doing the brakes for now if I can, but I don't want to crash the thing or it be unsafe until then.

    (I know this is a JL too btw)

    Screen Shot 2019-07-02 at 9.49.15 PM.jpg
     
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  16. Jul 2, 2019 at 6:59 PM
    #16
    The4x4Guys

    The4x4Guys Well-Known Member

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    First, congrats on the purchases to date, they are all first class (I should know, we sell all of those). I had Fox shock on the 2015 JKUR that I showed (yellow one) and I have Fox shocks on the JLUR, good choices.

    Do all this a step at a time is a good plan. Get the lift installed and see how you feel then about tires. While 35's are my personal recommendation, the real answer is dependent on what you want to do with this Jeep. Keep in mind 80% of Jeep never leave the pavement, nothing to be ashamed of, just a fact. You likely could squeeze 37's on if you weren't worried about fully articulating the suspension doing serious rock crawling. If off road is in the plans and you truly desire 37's you'll just have to plan on down the road wear and tear and the re-gearing. While I love the looks of the big brake kits, as I said above, I would only buy and install all that is required, if I absolutely felt I needed it for safety, but again that is going to be usage dependent.

    One step at a time is what I keep telling myself, then once a month the credit card statement arrives and I have to temporarily halt my Jeep purchasing.
     
  17. Jul 2, 2019 at 7:10 PM
    #17
    JKBob 25

    JKBob 25 Well-Known Member

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    Nice rig dude. I like the lift and in combination with the wheels and tires. Nice stance.
    Opps....my bad. How could I forget @Blue Baby Sound . As always....awesome advice.
     
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  18. Jul 3, 2019 at 7:54 AM
    #18
    Blue Baby Sound

    Blue Baby Sound Well-Known Member

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    We had a '16 Willys (since wrecked) with the factory 17" and a 35 (315/70/17) w/2.5" lift. I LOVED the stance of that Jeep.

    pUcwIN_d802c51990c7c9c2cef77937dd904093b537b107.jpg
     
  19. Jul 3, 2019 at 8:27 AM
    #19
    Jdubya420

    Jdubya420 [OP] Member

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    That is not my Rig, just some inspiration....
     
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  20. Jul 3, 2019 at 8:39 AM
    #20
    Jdubya420

    Jdubya420 [OP] Member

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    Yea, I have no interest in doing serious rock crawling (not at this time at least), watching guys bouncing body panels off of all of those rocks makes me cringe, lol. I do want to do some off mild to intermediate off-roading though.
     
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