Stock Tailgate Strong Enough for 37" KO2?

[treillw]

Just picked up my JLURD and got some 37" KO2s put on it. I'm concerned about ruining the tailgate. I've read though multiple other threads on this subject to gather some information, but want to get some additional opinions. I have a Warn spare tire carrier on order, but it is backordered until September, likely at best.

My wheel tire combo weighs 103 pounds. From what I've read, the tailgate is rated for 83 pounds, per at least some recent edition of the owners manual. I've also heard that the door warping is the primary concern with the tailgate strength, not the hinges.

The KO2 makes solid contact with the stock bumper and the rubber isolators are compressed very well - the tire hits the bumper pretty well when closing the tailgate and you can see marks where it slides up and over the bumper. I don't see there being much wiggle in the spare as it bounces down the road - although there will inevitably be some.

Obviously I'm not to crazy about putting this spare on there, as I have already ordered a carrier. I'm just in a bind with it not being available.

Dynamic load allowance is 33% for bridge design. Therefore, the stock carrier can carry a static equivalent of 110 pounds safely (1.33 x 83#). My 37" tire would only give me a 7% allowance (110/103) for movement.

I imagine I'm right on the bubble of it being too much weight. I'd hate to ruin something on my brand new vehicle. Probably safest to take it off.

What are your thoughts? Maybe I can find a carrier elsewhere. I would like the front and rear bumpers to match though (I have a Warn front).

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[Terpsmandan]

I am running that tire as well. I have the Mopar tailgate reinforcement from the factory and I added a Teraflex HD adjustable tire carrier:

https://teraflex.com/jl-alpha-hd-ad...ount-kit-w-brake-light-camera-mounts-5x5.html

The weak link is the sheetmetal in the tailgate. That carrier per Teraflex is supposed to be ok without reinforcement to 100 lbs. Hope this helps.

 

[Reinen]

It's high risk without reinforcement. Especially if you ride trails that you need 37s for. You might get away with it as a mall crawler but if you actually use your 37s there's a good chance you can bend a non-reinforced stock tailgate.

I'd ignore your bridge dynamic load allowance calculation. Bridges don't get bounced over rocks and boulders. That's when your tailgate can get bent, not when the Jeep is parked.

 

[SlickRickMotoADV]

The tailgate weight limit is 85lbs including the spare. You're over that. Do what you will with that info.

Most of us would recommend a hinge upgrade like Rusty's or a bumper mounted carrier.

 

[CarbonSteel]

So I will give you my experiences:

I started with a 33". moved to a 35" and then later moved to a 37". I installed the Mopar tailgate reinforcement and spare tire relocation kit at the same time as the 35". The studs are pressed into the tire relocation kit and they eventually started puling out. I fabricated some new relocation plates from 5/16" stainless steel and backwelded studs into them.

It worked OK for a while, but the tailgate always rattled and over time, the tailgate reinforcement plate would loosen despite me keeping the 4 bolts incredibly tight. In the end, when using the OEM reinforcement, the tailgate remains a load bearing member and that would be fine IF the hinges were about a foot longer creating more leverage on the tailgate and spreading the load further out, but that is not the case.

Look at the photo below without the tire mounted. With the Mopar kit everything to the left of that red line is unsupported and the tailgate takes the weight/vibration. The CavFab holds 100% of the weight/vibration on the hinges and tub mount--meaning that if you left the tailgate off, the spare would still be 100% supported. The Mopar kit cannot do that.

EDIT: @Ehmsea reminded me the Mopar tailgate reinforcement plate goes under the edge of the OEM plastic tire carrier so the red line has been shifted to account for that. With that said, that still leaves more than 50% of the tailgate not supported because the relocation kit and its aluminum plates do not form a solid contiguous piece of metal.

Each of those bolt holes to the left of the red line are an area of potential movement and let us not forget the 8 bolts under the OEM carrier are tightening against plastic. Without question, the 4 bolts that go through OEM hinges bear the majority of the load and if they were spread out more or if there were 6 bolts in the hinges, the design may be a solid one. In my experience, it was not.

When I upgraded to 37" tires (BFG K02), it was never a consideration to use the Mopar kit. I sold it and installed a CavFab kit. I would highly recommend it for you. You will ultimately change the Mopar kit to something else and will have spent more money than needed.

Buy once and cry once...

 

[Jeepiner]

I'll be going with the Teraflex Alpha HD Hinged Spare Tire Carrier + Mount for 37's once my JLURD is in. Best on the market by far from an engineering perspective.

 

[treillw]

I'm taking it off. Not worth the risk.

How would the stock spare fare with three 37s on at the other locations? Would only use it to limp out of the mountains, if necessary.

Just trying to figure out if I should ditch the spare entirely, or what.

 

[treillw]

I'll be going with the Teraflex Alpha HD Hinged Spare Tire Carrier + Mount for 37's once my JLURD is in. Best on the market by far from an engineering perspective.

Is there an advantage to it vs the Warn carrier?

 

[ColoradoMike]

So I will give you my experiences:

I started with a 33". moved to a 35" and then later moved to a 37". I installed the Mopar tailgate reinforcement and spare tire relocation kit at the same time as the 35". The studs are pressed into the tire relocation kit and they eventually started puling out. I fabricated some new relocation plates from 5/16" stainless steel and backwelded studs into them.

It worked OK for a while, but the tailgate always rattled and over time, the tailgate reinforcement plate would loosen despite me keeping the 4 bolts incredibly tight. In the end, when using the OEM reinforcement, the tailgate remains a load bearing member and that would be fine IF the hinges were about a foot longer creating more leverage on the tailgate and spreading the load further out, but that is not the case.

Look at the photo below without the tire mounted. With the Mopar kit everything to the left of that red line is unsupported and the tailgate takes the weight/vibration. The CavFab holds 100% of the weight/vibration on the hinges and tub mount--meaning that if you left the tailgate off, the spare would still be 100% supported. The Mopar kit cannot do that.

When I upgraded to 37" tires (BFG K02), it was never a consideration to use the Mopar kit. I sold it and installed a CavFab kit. I would highly recommend it for you. You will ultimately change the Mopar kit to something else and will have spent more money than needed.

Buy once and cry once...

View attachment 600899

Interesting... thanks for sharing.
What you have said makes me think that any of us who have ordered an Xtreme Recon package are going to run into trouble. It will come with KO2 35s and the Mopar relocation kit/reinforcement kit.
So unless they have changed something (what year is yours?) or perhaps your 35s/wheel combo were heavier than the XR tire/wheel combo... I would have to think we'll have trouble. Unless they have changed the relo kit or your kit wasn't installed quite right.
Did you ever experience damage to your tailgate, have trouble closing it, any other problems like that? Or did you just have the issue of a rattle and needing to periodically re-tighten?
Any 21 or 22 XR owners out there have any experience/comments?

 

[Jeepiner]

Is there an advantage to it vs the Warn carrier?

The Teraflex option strengthens the hinge of the tailgate, increasing it's max load capacity. The spare tire mount attaches to that, like the OEM/mopar options. And based on all the research I've done, it makes no noise. Plus it looks better than any other aftermarket carrier.

The Warn tire carrier attaches to the bumper, and IIRC people have reported issues with it making noise.

 

[treillw]

It's high risk without reinforcement. Especially if you ride trails that you need 37s for. You might get away with it as a mall crawler but if you actually use your 37s there's a good chance you can bend a non-reinforced stock tailgate.

I'd ignore your bridge dynamic load allowance calculation. Bridges don't get bounced over rocks and boulders. That's when your tailgate can get bent, not when the Jeep is parked.

But bridges have 80,000 pound tractor trailers smashing into them at 80 mph plus.... I think that hurts a little more than dropping off a boulder.

 

[treillw]

The Teraflex option strengthens the hinge of the tailgate, increasing it's max load capacity. The spare tire mount attaches to that, like the OEM/mopar options. And based on all the research I've done, it makes no noise. Plus it looks better than any other aftermarket carrier.

The Warn tire carrier attaches to the bumper, and IIRC people have reported issues with it making noise.

I assume it's no issue to use the teraflex reinforcement with the Warn rear bumper?

 

[CarbonSteel]

@ColoradoMike :

What you have said makes me think that any of us who have ordered an Xtreme Recon package are going to run into trouble. It will come with KO2 35s and the Mopar relocation kit/reinforcement kit. I think you will have issues over time, there is no avoiding it--the load is too much for such a short support span.

So unless they have changed something (what year is yours?) or perhaps your 35s/wheel combo were heavier than the XR tire/wheel combo. Mine was a 2019 and the Mopar kit was bought in 2020. My 35" tire/wheel combo was 4.1 pounds heavier than the stock 33" tire and wheel combo.

I think the 35" tires I chose were pretty light as 35's go and have to be inline with the weight of the Recon package since those beadlocks are likely heavier than the Moab/Willys wheels I had.

I spent a lot of time researching on ways to keep my unsprung weight down even going as far as building out a tire comparison sheet for 35", 37", and 40" tires:







Below you can see my OEM weight (84.4 pounds) versus 35" (88.5 pounds--the spacer weight does not count for the tailgate load) versus 37" (91.3 pounds):

I would have to think we'll have trouble. Unless they have changed the relo kit or your kit wasn't installed quite right. In the end, I think you will experience the same loosening and rattling that I did. There is only one way to install the kit--it is only 4 bolts and you align the tailgate, install the bolts and torque them.

Did you ever experience damage to your tailgate, have trouble closing it, any other problems like that? Or did you just have the issue of a rattle and needing to periodically re-tighten? No damage, but over time it would start to sag due to the 4 bolts loosening and there was no way (including using blue and later orange loctite) to keep them "permanently" tight. The weight and load will not allow it on a span of bolts as short as the stock hinges have.

 

[Reinen]

But bridges have 80,000 pound tractor trailers smashing into them at 80 mph plus.... I think that hurts a little more than dropping off a boulder.

Relatively speaking, that's like throwing a rock at your spare. Now try lifting the entire bridge up and drop it a few feet. See if something bends.

I'm not trying to fight you on this. It's your tailgate, not mine. I'm just saying dynamic motion requires a lot of leeway. Keep in mind that with roof racks the dynamic weight limit is typically 1/3 that of static weight limit. The same is going to apply to the tailgate & spare. If it might be questionable, it probably is. Err towards over-reinforcement.

 

[DHW]

Interesting... thanks for sharing.
What you have said makes me think that any of us who have ordered an Xtreme Recon package are going to run into trouble. It will come with KO2 35s and the Mopar relocation kit/reinforcement kit.

I've had a 35' KO2 on a Mopar beadlock on my tailgate (with the Mopar relocation/reinforcement kit) for about 3 years now with no problems.

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