Roof rack system load ratings needed

[NJRadioGuy]

As I've referenced in a couple of previous questions, I'm looking to purchase and install a roof rack system for my 22 JLUR hardtop but I have a question that is nearly impossible to find the correct answer to. Having watched videos from a few years ago by Australian overlanders Tyler Thompson and Ronny Dahl, as well as a tremendously funny engineer named John Cadogan, it seems Rhino Racks have a load issue. Or more specifically, the vehicles to which the racks are mounted have a load issue. And this is where things get real fuzzy for me, and I don't feel comfortable proceeding until I am able to find the answers I need.

In the case of my JL, the manual states the vehicle roof's load limit is 100 pounds (p. 98 of the manual under the heading of Roof Luggage Rack, if equipped--excerpted below), and I'm assuming that's the hardtop since it's in the printed manual for my Jeep.

What I cannot find is whether or not that factors in the backbone system that attaches through the supporting feet and brackets to the frame of the vehicle after drilling through the hardtop. It would seem to me that it would safely carry a fair bit more weight supported by the frame, but I cannot find any published ratings anywhere that stipulate the static, dynamic, and off-road dynamic ratings of a Rhino Rack system mounted in that fashion. Can anybody point me to a definitive reference, either by a rack manufacturer or by Jeep that specifies?

Rhino Rack's own load calculator (https://www.rhinorack.com/en-us/load-rating-calculator), for the system I am considering purchasing, indicates that the maximum offroad load rating is only 66 pounds (see below). Obviously many people are bringing their heavy RTTs, Maxtrax, cargo boxes, solar panels and any manner of other gear up top without it destroying their Jeeps in a mishap, so I'm guessing the carrying weight bolted to the frame is much higher...but I just cannot find anything in writing to confirm this to be the case. Can anyone assist in this regard? Please and thanks.

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[Av8Chuck]

This topic comes up frequently. Some Jeep JL owners strictly follow the letter of the law, while others adhere to the intent behind the regulations and specifications. If you're running 35" or 37" tires with a 4" lift, your primary concern shouldn't be the weight limit—it should be the center of gravity. Adding excessive weight too high on a lifted Jeep can make driving noticeably more unstable.

I have an iKamper, one of the heavier rooftop tents (RTTs), along with a 270-degree awning and a few other tools and attachments, bringing the total added weight to around 200 pounds. In five years, I’ve had zero issues. I no longer keep the RTT mounted full-time due to fuel economy, but setups like mine are fairly common. I can't recall anyone having trouble with weight limits.

As for the Backbone system, it mounts directly to the body in the same way as the roll bar and connects to the rack. It’s likely made of 1/4" steel, which should easily support five to six hundred pounds. The real concerns arise if you get into a head-on collision with a semi or drive recklessly off-road.

Manufacturers likely reduce weight ratings by a factor of four to limit liability. I’m not suggesting you load 400 pounds on top, but if this level of risk concerns you, a trailer might be a better option.

 

[NJRadioGuy]

It’s likely made of 1/4" steel, which should easily support five to six hundred pounds. The real concerns arise if you get into a head-on collision with a semi or drive recklessly off-road.

Keyword: should. Going by your forum handle I'm guessing you've earned your wings at some point, so I'll equate my concerns here to weight and balance. The POH is clear as to what is acceptable and what isn't, and while you can almost certainly be 25 pounds overweight or have a slightly aft C/G and get away with it, there will inevitably be that one time where you won't, and soon the NTSB is doing a case study of what went so tragically wrong.

Granted the stakes are likely far lower here, but my analogy is that there is no Jeep or Rhino/etc equivalent to the POH so we can make an educated decision about whether this model rack or that will be suitable for purpose.

Manufacturers likely reduce weight ratings by a factor of four to limit liability. I’m not suggesting you load 400 pounds on top...

To start off with I won't have a RTT so my loads will be far less than 400#, although more than what the company's load calculator yields for my model vehicle (68# dynamic/offroad). They are not factoring in the braces against the frame, and the paranoid science geek in me really wants something close to a definitive answer, which the manufacturer won't provide.

I agree, a modest RTT and awning, plus the rack system itself, is far over what Rhino states on their website and there aren't scads of reports of rollovers so it must be safe, however it would be great to see something in writing to confirm it. I'm sure these loads have been calculated out at some point, but I'll be darned if I can find any studies or even sales literature to chase down.

 

[OminousSkitter]

The weight ratings aren’t about rollover but about what reasonably won’t cause damage to your roof/body/rack.

Given how much of a rollover is not just load dependent but also operator and terrain dependent, no manufacturer will ever give you what you want. You can roll over a stock, empty jeep on level ground if you try—I believe there’s even a friendly sticker on the visor about that.

What I can say is the weight limit in the owners manual does not account for any non-gutter-mounted roof racks. The owners manual is giving what Jeep thinks is a safe load that won’t damage the hardtop—not a safe load for rollovers. Roof racks that tie into the body (e.g. RR backbone), ones that tie into the roll bars (e.g. Maximus-3), exoframes, etc can exceed the owners manual limits.

 

[azjl#3]

Consider 4 huge adults. Probably a higher load center than couple hundred on roof.

Also, the dynamic vehicle control is pretty good, and industry leading because it was designed way back when, when jeeps rolled taking low speed corners.

 

[NJRadioGuy]

The weight ratings aren’t about rollover but about what reasonably won’t cause damage to your roof/body/rack.

That's the value I'm looking for, the "won't cause damage to the vehicle" numbers, not the rollover value, which, as you say, is highly dependent on a myriad of other factors.

RR lists what their products can support, but without factoring the system being anchored to the body. It's that latter value that I'm trying to get a solid number on.

 

[OminousSkitter]

That's the value I'm looking for, the "won't cause damage to the vehicle" numbers, not the rollover value, which, as you say, is highly dependent on a myriad of other factors.

RR lists what their products can support, but without factoring the system being anchored to the body. It's that latter value that I'm trying to get a solid number on.

I’m a little confused. I went to their load rating calculator and entered a 4dr JL and had the option to specify the heavy duty mounting system and get numbers back (179lbs off-road)

Granted, I said the owners manual says it can support 1000lbs because their products typically say “use the calculator and look at the owners manual; use whichever is lower”. I didn’t want the owners manual number changing the calculators result.

Side note: today I learned they offer a “backbone” system that is gutter mounted and doesn’t use its namesake.

 

[NJRadioGuy]

I’m a little confused. I went to their load rating calculator and entered a 4dr JL and had the option to specify the heavy duty mounting system and get numbers back (179lbs off-road)

Where did you see 179 lbs? I screen-shotted my response from their calculator in my original post.

Granted, I said the owners manual says it can support 1000lbs because their products typically say “use the calculator and look at the owners manual; use whichever is lower”. I didn’t want the owners manual number changing the calculators result.

The owner's manual says 100 (one hundred) pounds, not one thousand!

 

[Av8Chuck]

Keyword: should. Going by your forum handle I'm guessing you've earned your wings at some point, so I'll equate my concerns here to weight and balance. The POH is clear as to what is acceptable and what isn't, and while you can almost certainly be 25 pounds overweight or have a slightly aft C/G and get away with it, there will inevitably be that one time where you won't, and soon the NTSB is doing a case study of what went so tragically wrong.

Like i said earlier, this topic has been debated so many times and to my knowledge no one has found the numbers your looking for.

People aren’t going to agree with this but I am a helicopter pilot, we used the POH as a recommendation. I flew UH-1H and AH-1S in the Army. When it was hot, hi-DA and full fuel the door gunners would run alongside until either we started climbing or they couldn’t run any faster then they’d jump in. As long as the egt wasn't to high and the bleedbands didn’t open we were good to go.

People aren’t going to indemnify you with the numbers your looking for, too many variables. Just use common sense and be safe.

 

[OminousSkitter]

Where did you see 179 lbs? I screen-shotted my response from their calculator in my original post.

Idk what RLT600 legs are.

[RANT]
I hate their website with a passion. Model numbers on one page don’t match model numbers on another, they have specific instructions for one model but tell you to use the calculator for ratings; they use more text/ink to say that than just saying WTH their ratings are.
[/RANT]

Anyway, I selected what I *think* the backbone system that uses metal around the windows and bolts to the body (and you have to drill through the roof to install) is called. That one said 179lbs

The owner's manual says 100 (one hundred) pounds, not one thousand!

I assume you read what I wrote since you quoted it. Yes, it’s 100 not 1000, and I explained my reasons.

If you want easy to find numbers, go with a different company. @Maximus-3 gives you numbers for their pioneer platform mounting solution:

• Dynamic Load: 300 pounds. Static Load: over 900 pounds distributed, tested & proven.

 

[NJRadioGuy]

Like i said earlier, this topic has been debated so many times and to my knowledge no one has found the numbers your looking for. <snip>
People aren’t going to indemnify you with the numbers your looking for, too many variables. Just use common sense and be safe.

It really is unfortunate that neither the manufacturer nor online resources would have even a ballpark value for this (somewhere between 300 and 500 pounds, and here's why kinda thing).

People aren’t going to agree with this but I am a helicopter pilot, we used the POH as a recommendation. [/QUOTE]

Well that's the difference right there. Helicopters don't actually fly. They're just so ugly that the ground repels them Nothing that fancy here, just a bog-standard PP-ASEL with about 750 hours PIC before my Class 3 medical went bye-bye. I had to show my instructors, examiner and later, the FBO folks my W/B calculations before I got the keys and paperwork before every flight, and they better be well under max values. I'm saying all this basically to explain why I'm a stickler for this kind of info. I see a ton of Jeeps with racks and RTTs/awnings/etc, so it must be safe, but to what degree? I'm probably fixing to put about 75-80# up top initially so I know I'll be well under, but still....

 

[Hard Rock Jeep]

I have the Rhino Rack Backbone three bar system on two jeeps. Here is the photo of the cover of the instruction manual. They say the max Static Load is 800 pounds, the max load for highway use is 264 pounds and the max load for off-road is 176 pounds. If you choose to go this route, DM me as I can provide some important additional information.

 

[Willing&Able]

I've had the RR w backbone system for about four years on two different Jeeps. With my current Jeep I had a 200# tent on top and even off-roading never had any issues. See below.

I did recently end up moving to a small trailer for the tent. While more money, a much better solution for me.

 

[Av8Chuck]

That’s the direction I decided to go as well.

 

[Av8Chuck]

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