2024 Jeep Rubicon JLUR X 37s Upgrade: Re-Gear, Spacers & Lift?

You’re right at the edge of what the JLUR X can do “stock plus” with 37s. The good news: your 4.56s and X package make 37s doable without an immediate re-gear, but there are tradeoffs. Biggest hidden costs are bump stop/clearance work and possibly wheels or spacers to keep 37s out of the control arms and fenders at full flex.

Top recommendations (ranked)

1. Run 37s on stock 4.56s first, no re-gear (test it)

   • For highway + moderate trails, 4.56 with the 8‑speed is livable on 37s.
   • Cost: $0 beyond tires/mount/balance.
   • Difficulty: DIY decision, shop mounts tires.
   • Expect: more shifting on grades, you’ll use 7th/6th more, but it’s not a dog. If you hate it, then re-gear to 4.88 or 5.13 later.

2. Skip wheel spacers if you can; use proper offset wheels instead

   • If you’re on the factory XR beadlocks/17s, they’re already more aggressive offset than base Rubicon wheels and usually clear 37s better.
   • If you’re on standard Rubicon wheels, 37s will likely rub control arms and sway bar at full lock. You’ll want ~0 to -12 mm offset wheels or 1.5" hub-centric spacers.
   • Cost: wheels $800–$1,600 set, spacers $150–$250 set.
   • Difficulty: DIY-friendly with torque wrench.
   • Safety note: if you do spacers, use quality hub-centric (e.g. Spidertrax, Teraflex), torque correctly, and re-torque after 50–100 miles.

3. Bump stops and minor trimming to keep 37s off the fenders

   • Your ~1.5" factory lift and highline Rubicon fenders are better than a base JL, but 37s at full stuff can still kiss the inner liners and pinch seam.
   • Add front and rear bump stop extensions and check/adjust steering stops.
   • Cost: $50–$200 in parts.
   • Difficulty: DIY moderate (need to pull coils or use spring compressors).
   • This is the minimum to keep from eating fenders on hard articulation.

4. If you want full articulation with 37s, go to a true 2.5"–3" lift

   • For Colorado trails where you’ll flex it, a quality 2.5" kit (MetalCloak, Teraflex, AEV, Clayton, etc.) with proper bump stops and longer shocks is the sweet spot.
   • That plus your factory ~1.5" net puts you in a very safe place for 37s.
   • Cost: $1,200–$3,000 depending on shocks and arms.
   • Difficulty: Pro recommended, especially for alignment, caster, and driveshaft angles.
   • This is where it stops being “shoehorned 37s” and becomes “proper 37 setup.”

5. Re-gear only if you hate the drive or add a lot of weight

   • If you armor it up, add steel bumpers, winch, and it feels sluggish or hunts gears, then 4.88 or 5.13 is worth it.
   • For a mostly stock-weight JLUR X on 37s, 4.56 is acceptable; 4.88 is “nice,” 5.13 is “peppy but revvier” at highway speeds.
   • Cost: $2,000–$3,000+ installed (both axles, quality shop).
   • Difficulty: Pro only.
   • I’d drive it on 37s first before dropping gear money.

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Do you need to re-gear for 37s with 4.56?

• With the 8‑speed auto, 4.56 and 37s is usable for:
  • Highway at 65–75 mph.
  • Moderate Colorado trails.
• You’ll notice:
  • More downshifting on long grades.
  • Slower acceleration vs stock tires.
  • More time in 7th/6th instead of 8th on the highway.

My call:

• No, you don’t “need” to re-gear just because you go to 37s.
• Yes, you might “want” to re-gear if:
  • You add heavy armor, racks, camping gear regularly.
  • You tow.
  • You’re picky about throttle response and don’t like the trans hunting.

If/when you re-gear:

• 4.88: Good all-around for mixed highway/trails on 37s.
• 5.13: Better for heavy rigs and lots of crawling, a bit busier on the interstate.

I won’t give a ratio without knowing your engine, but I’m assuming 2.0T or 3.6; both live fine on 4.56/37s with the 8‑speed.

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Will you need wheel spacers?

Depends on which wheels you have now:

• Factory XR / “X” wheels (wider, more aggressive offset):

  • Many folks run 37s on these with no spacers, just bump stops and maybe a bit of lock-limit.
  • You still need to check:
    • Full lock, full stuff: inner sidewall vs control arms and sway bar.
    • Outer sidewall vs fender flare and inner liner.

• Standard Rubicon wheels (more conservative offset):

  • 37s almost always rub the lower control arms and/or sway bar at full lock.
  • You’ll likely need:
    • 1.5" hub-centric spacers, or
    • New wheels with 0 to -12 mm offset and 4.5–4.75" backspacing.

My call:

• If you’re still on factory X wheels, try the 37s first, no spacers, and test:
  • Full lock left/right in a parking lot.
  • Flex it on a ramp/ditch and look for contact.
• If they rub arms or sway bar:
  • Go to proper offset wheels if budget allows.
  • Spacers are fine if you use quality hub-centric and torque them right.

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Do you need more lift for full articulation on 37s?

You’ve got:

• ~1.5" factory lift (X package).
• Highline Rubicon fenders (more clearance than Sport/Sahara).

That’s better than a base JL, but 37s at full flex are big.

On-road / mild flex:

• You can run 37s with:
  • Your current lift.
  • Proper bump stops.
  • Maybe a little inner liner massaging.
• You’ll be fine for “moderate” use if you’re not stuffing it hard all the time.

Off-road / full articulation:

• To truly use all the travel without:
  • Smashing fenders.
  • Eating liners.
  • Bending pinch seams.
• You really want:
  • 2.5"–3" true suspension lift with:
    • Correct bump stop lengths.
    • Shocks matched to travel.
    • Ideally, front lower control arms to get caster back in spec.

My call:

• For moderate Colorado trails (think easy to mid-level passes, not constant rock gardens):
  • You can get away with stock X lift + 37s + bump stops if you drive smart and accept some limited uptravel.
• If you want to hammer it, flex it hard, and not worry, go to a quality 2.5" kit and set bump stops correctly.

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Compatibility & prerequisites

• Confirm exact wheels you have (XR/X vs standard Rubicon) before buying spacers or new wheels.
• Check tire actual size; some “37s” measure closer to 36", some over 37".
• Make sure any lift kit is JLUR-specific and 2024-compatible (track bar bracket, sway bar links, etc.).
• If you re-gear:
  • Use a shop that knows JL Dana 44s and sets up gears all the time.
  • Plan for speedo recalibration and possibly TCM/ECM adaptation.
• After lift/37s:
  • Get a 4‑wheel alignment and check caster.
  • Check front driveshaft clearance at full droop with bigger lifts.

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Realistic expectations & tradeoffs

• Power/drive feel:

  • 37s + 4.56 = slower, but not miserable.
  • Re-gear later if it annoys you, not before.

• MPG:

  • Expect a noticeable drop going to 37s, especially with more rolling resistance and weight.

• Braking & handling:

  • 37s add rotating mass; braking distances increase.
  • Steering will feel heavier; any slop in suspension will show up more.

• Wear & tear:

  • Ball joints, tie rods, unit bearings, and driveshafts all see more load.
  • Keep up on torque checks and inspections, especially with spacers.

• Ride & NVH:

  • Bigger, more aggressive 37s = more noise and a bit harsher ride.
  • A good 2.5" kit can actually ride better than stock if you pick decent shocks.

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A few questions that would refine this

1. Which engine and transmission do you have (2.0T, 3.6, 4xe; auto/manual)?
2. Are you on the factory XR/X wheels, or standard Rubicon wheels, or aftermarket?
3. How “moderate” are your Colorado trails — more like easy passes and forest roads, or do you hit real rock gardens regularly?

Answer those and I can tell you:

• Whether I’d personally re-gear at all on your setup.
• Whether you can realistically skip spacers/wheels.
• Exactly how much lift/bump stop I’d run to keep your 37s from eating the Jeep.