2021 JLUR plan on upgrading to 37in tires, questions

JR-G

New member
2021JLUR
Will be getting a 3.5in lift soon. (Teraflex or Metalcloak or combo of both)
Will upgrade to larger tire from stock 33in KO2, 35in min or 37in max.
personally would like to put the 37 on, but will the oem axle's be ok with this?
(2021 front has CV joints)
I believe I will be using drop brackets to keep steering geometry the same.

Some places say using 8in wheel will work, others say 8.5in and another says use 9in.
What would be the best? (I don't believe the oem 8in will do the job)

Is there any other things to consider if using 37in?
(I know about the tire carrier but I will deal with that unless someone has a good idea that isn't expensive like Teraflex option)
(also plan on getting a Tazer to remap the cpu etc.)
 

CalSgt

Hooked
Wheel backspace is more important than wheel width when fitting far larger tires, I was able to fit 37x13.50's using a 4.75" BS wheel with just a little rub while flexed out at a full turn. They rubbed the EVO lower control arms just enough to shine the paint off in one spot. There are a few forum members that have fitted 37's on stock Rubicon wheels using wheel spacers.

There are several companies that make spare tire spacer kits to move the tire up and away from the tailgate enough to make them fit, here's Eddies how to video link:
http://wayalife.com/threads/video-j...7-spare-tire-on-a-jl-wrangler-tailgate.52858/

Not sure about CV joints in the front axle, I thought only some of the non Rubicon models used those. My stock u-joint type axles held up to three trips in and out of the Rubicon (almost), a week in Moab, and some local wheeling trips just fine, they probably would have lasted several more if I didn't get stupid. Anyway if they're not up to the task Spicer sells chromoly upgrade front shafts for about $600 or so.

Also, neither of the lift kit manufactures you mention have the greatest reputation around the forum. I have no personal experience with them, but have been very pleased with EVO Manufacturing stuff.


ETA: When choosing backspace lees BS makes more room for tires but adds stress to ball joints, unit bearings, and steering components making it harder to turn while at a complete stop.
 

Ddays

Hooked
Helped Weebz install an EVO 3.5 Enforcer Stage 1 kit on Andy5160's JLUR a couple weeks ago. He used Core 4x4 control arms instead of the EVO's and I have to say I was very impressed. When it's time to do this on my JL its exactly what I'm doing. It's worth taking a look at. Personally, I wouldn't recommend the drop brackets. The control arms were plenty flat after the lift was installed. All you're doing is adding anchors to drag on everything when you wheel.

Rusty's Offroad makes the best hinged tire carrier that I've seen for the JL's. I've had mine on the JL for over a year now and I'm impressed with it as well. I've seen the EVO one and honestly, Rusty's beats it hands down.

Stock axles will be fine with the 37's. I've been running them for almost 2 years and it's been put through it's paces. There are countless guys running 37's just fine.
 

MericaMade

Active Member
On the JL with 44s I wouldn't worry about running 37s. Like other have said look at the Evo 3.5 its a great kit and straight foward install.
 

JR-G

New member
Wheel backspace is more important than wheel width when fitting far larger tires, I was able to fit 37x13.50's using a 4.75" BS wheel with just a little rub while flexed out at a full turn. They rubbed the EVO lower control arms just enough to shine the paint off in one spot. There are a few forum members that have fitted 37's on stock Rubicon wheels using wheel spacers.

There are several companies that make spare tire spacer kits to move the tire up and away from the tailgate enough to make them fit, here's Eddies how to video link:
http://wayalife.com/threads/video-j...7-spare-tire-on-a-jl-wrangler-tailgate.52858/

Not sure about CV joints in the front axle, I thought only some of the non Rubicon models used those. My stock u-joint type axles held up to three trips in and out of the Rubicon (almost), a week in Moab, and some local wheeling trips just fine, they probably would have lasted several more if I didn't get stupid. Anyway if they're not up to the task Spicer sells chromoly upgrade front shafts for about $600 or so.

Also, neither of the lift kit manufactures you mention have the greatest reputation around the forum. I have no personal experience with them, but have been very pleased with EVO Manufacturing stuff.


ETA: When choosing backspace lees BS makes more room for tires but adds stress to ball joints, unit bearings, and steering components making it harder to turn while at a complete stop.
 

JR-G

New member
I'm from Canada so somethings aren't the same.
you call it backspace we call it negative offset I believe.
Thanks for the info on tire carrier.
I don't know about the CV joints, it definitely is Rubicon though.
That's interesting about the company's, from what I have gathered these 2 are pretty much the top here.
Ideally the centre of the tire should be directly over the wheel bearings?
I will look into EVO, thanks.
 

JR-G

New member
Helped Weebz install an EVO 3.5 Enforcer Stage 1 kit on Andy5160's JLUR a couple weeks ago. He used Core 4x4 control arms instead of the EVO's and I have to say I was very impressed. When it's time to do this on my JL its exactly what I'm doing. It's worth taking a look at. Personally, I wouldn't recommend the drop brackets. The control arms were plenty flat after the lift was installed. All you're doing is adding anchors to drag on everything when you wheel.

Rusty's Offroad makes the best hinged tire carrier that I've seen for the JL's. I've had mine on the JL for over a year now and I'm impressed with it as well. I've seen the EVO one and honestly, Rusty's beats it hands down.

Stock axles will be fine with the 37's. I've been running them for almost 2 years and it's been put through it's paces. There are countless guys running 37's just fine.
 

JR-G

New member
what does it drive like on road compared to stock?
I will look into Rusty's.
That is what I am coming up with that the 37's wouldn't be an issue with axles.
 

CalSgt

Hooked
I'm from Canada so somethings aren't the same.
you call it backspace we call it negative offset I believe.
Thanks for the info on tire carrier.
I don't know about the CV joints, it definitely is Rubicon though.
That's interesting about the company's, from what I have gathered these 2 are pretty much the top here.
Ideally the centre of the tire should be directly over the wheel bearings?
I will look into EVO, thanks.
Offset only references the measurement from the center of the wheel to the mounting surface at the hub. Two different width wheels can both be zero offset (or even -48mm) and each have different backspace. Most aftermarket wheel companies advertise both. Most wheels that are advertised to fit your jeep are between 3.5"-4.75" BS, factory is probably between 5-6".

The center of the tire (where it contacts the pavement) should intersect the imaginary line between the upper and lower ball joint, resulting in zero scrub radius. As you space the center of the wheel away from the vehicle scrub radius increases. When changing tire height and wheel backspace to clear the new taller & wider tire this is nearly impossible but the best bet is to run a wheel with the least amount of backspace that still allows the tire to not rub.

Here's the question... What do you plan to do with it?
 

JR-G

New member
Offset only references the measurement from the center of the wheel to the mounting surface at the hub. Two different width wheels can both be zero offset (or even -48mm) and each have different backspace. Most aftermarket wheel companies advertise both. Most wheels that are advertised to fit your jeep are between 3.5"-4.75" BS, factory is probably between 5-6".

The center of the tire (where it contacts the pavement) should intersect the imaginary line between the upper and lower ball joint, resulting in zero scrub radius. As you space the center of the wheel away from the vehicle scrub radius increases. When changing tire height and wheel backspace to clear the new taller & wider tire this is nearly impossible but the best bet is to run a wheel with the least amount of backspace that still allows the tire to not rub.

Here's the question... What do you plan to do with it?
Simple,
offroading😁
But seriously I like more technical trails including light rock crawling.
Use the fsr to find trails and explore. Not a mudder but if the trail has mud in the way so be it.
Winter is around the corner so some snow runs.
 

Ddays

Hooked
what does it drive like on road compared to stock?
I will look into Rusty's.
That is what I am coming up with that the 37's wouldn't be an issue with axles.
I didn't get the chance to drive Andy's Jeep, but he drove it from Baltimore to Rausch Creek, and then to Philly the next day. He was very satisfied with it. He said it drove better than stock.
 

JR-G

New member
Offset only references the measurement from the center of the wheel to the mounting surface at the hub. Two different width wheels can both be zero offset (or even -48mm) and each have different backspace. Most aftermarket wheel companies advertise both. Most wheels that are advertised to fit your jeep are between 3.5"-4.75" BS, factory is probably between 5-6".

The center of the tire (where it contacts the pavement) should intersect the imaginary line between the upper and lower ball joint, resulting in zero scrub radius. As you space the center of the wheel away from the vehicle scrub radius increases. When changing tire height and wheel backspace to clear the new taller & wider tire this is nearly impossible but the best bet is to run a wheel with the least amount of backspace that still allows the tire to not rub.

Here's the question... What do you plan to do with it?
I get the difference between negative offset and backspacing now.
 

JR-G

New member
I had some info from another site, does this person have any valid points?

"at 37s for off road where 37s are needed the axle shafts may be an issue. We had a 2020 JLUR on 37s on our Rubicon last June run break the front axle shaft long side. Steering wont have enough power.

Street the stock gears wont be enough, lose of usable overdrive. lose of power. 37s you need 4.88 gears to be even close to stock. 4.1 gears you have any type of towing left in it. gears to MORE for street then off road for U. You have a 4:1 low that will that off road will be enough. But that is off road in low.

wheels will be very hard to find after market in a 8" wide and have the back space you will need. Most wheels will be in the 17x9< most all makers of 37x12.5x17 will be a 8.5 specs and most the wheels you will find will be 8.5-10. I would not get a 10 wide.

lifts at 3.5 + will need a front drive shaft of DC typs (three u joints). These type shaft it best to have adjustable arms over drop brackets. DP brackets you loose 3" of ground clearance. Off road that ey can hang you up on rocks< though i have a feeling it may not apply? "
 

MericaMade

Active Member
I had some info from another site, does this person have any valid points?

"at 37s for off road where 37s are needed the axle shafts may be an issue. We had a 2020 JLUR on 37s on our Rubicon last June run break the front axle shaft long side. Steering wont have enough power.
MistresJLU is currently running 37 toyos on 44front and stock steering with Zero issues so far.
Street the stock gears wont be enough, lose of usable overdrive. lose of power. 37s you need 4.88 gears to be even close to stock. 4.1 gears you have any type of towing left in it. gears to MORE for street then off road for U. You have a 4:1 low that will that off road will be enough. But that is off road in low.
The 4.10s are fine but you will want to move up to 4.88 or 5.13s. Again on Mistress the 4.10s on 37s were fine but the 5.13s made it a lot better.
wheels will be very hard to find after market in a 8" wide and have the back space you will need. Most wheels will be in the 17x9< most all makers of 37x12.5x17 will be a 8.5 specs and most the wheels you will find will be 8.5-10. I would not get a 10 wide.
8.5 or 9 is fine. I have run both with no issues on 37s and 40s.
lifts at 3.5 + will need a front drive shaft of DC typs (three u joints). These type shaft it best to have adjustable arms over drop brackets. DP brackets you loose 3" of ground clearance. Off road that ey can hang you up on rocks< though i have a feeling it may not apply? "
I don't think this is true with the JL but is true for the JK regarding drive shafts. Again we have Mistress setup about 3.5 inches on EVO CO's running stock drive shafts on 37s with zero issues. Yes do adjustable arms over drop brackets.
 

CalSgt

Hooked
I second all of this ^^^

I also have a 3.5 lift with Evo CO's and a factory driveshaft with no problems.
Me too...

30K miles and plenty of off-roading with 37's and stock 44's, one shaft break due to stupidity. Would not have broken had I just got someone to assist with recovery.

25K miles on the 4.10 gears just fine, however I do like the 4.88 gearing better

15K miles on 3.5 EVO coils and stock driveshafts with no issue, I only changed them because I went to coilover suspension.
 

BlueRubicon

Member
IMO everything but the axles is the limiting factor. I've been running 37's on JLUR hard for 2 years now. D44 is strong if you don't drive like an asshole. My rear is stock and the front I put in RCV's and eliminated the FAD. I also eliminated the shit ball joints and aluminum knuckles. Front linkage all new. You could probably run forties on the M210 and 220...again as long as you don't drive like an idiot. Steering power is fine without RAM assist. Sure, when your wedged on rocks climbing you often cannot turn the steering wheel, but I suspect any rig without RAM will experience this. I can still get into 8th gear on the highway with 37's and 4:10's. So I am not in any hurry to change.
 
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