Roof Rack Load Limits : On-Road vs Off-Road (1 Viewer)

TheGrrrrr

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I'll start this thread with a video that got me thinking about roof load limits. All I have ever seen or looked at are static vs dynamic limits, but it seems the dynamic limits should be broken out into two separate numbers: On-Road vs Off-Road. Take a look at the whiteboard portion of this video and then lets do some math.




The best estimate I have found for the dynamic (on-road) roof carrying capacity of the 200 series is 200kg (440lbs), important to note this is not the capacity of the bars, but the roof itself so far as I can find.

Assuming this video is correct, so just for illustration purposes, lets say that off-road that dynamic capacity is reduced by 1/3 which brings it to 133kg (293lbs). Assume you have the full size Rhino Rack as I do, which they say is 41lbs with the backbones system.

Off-road Roof Limit = 293lbs
Rhino-Rack w/ Backbone = 41lbs

Actual Off-road Capacity = 252lbs

Bush Company Awning = 61lbs
MaxTrax (2) and mounting hardware = 18lbs
Light Bar and Mounting hardware = 12lbs
Solar Panel = 6lbs

That leaves me with: 153lbs of off-road carrying capacity on the roof. Not bad, but certainly not enough to carry most RTTs with anything attached to them.


This seems like a problem. Anyone have any thoughts about this? My specific example not withstanding.

Edited to fix a metric conversion.
 
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Basically the same numbers I came up with this morning after watching Ronnys video and Tylers as well who asl suffered a roof rack failure.
you will need to add in mount hardware and wiring to your totals but its in the ball park for what a roof rack can actually hold safely.

My calc's were based on a K9 platform, which they rate to 500 lbs dynamic, but of course that is over the roof load limit, so irrelevant other that it is rated over the capacity of what it is attached to so you are not limited by the racks capacity only the Roofs.
 

gaijin

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I'll start this thread with a video that got me thinking about roof load limits. All I have ever seen or looked at are static vs dynamic limits, but it seems the dynamic limits should be broken out into two separate numbers: On-Road vs Off-Road. Take a look at the whiteboard portion of this video and then lets do some math.




The best estimate I have found for the dynamic (on-road) roof carrying capacity of the 200 series is 200kg (440lbs), important to note this is not the capacity of the bars, but the roof itself so far as I can find.

Assuming this video is correct, so just for illustration purposes, lets say that off-road that dynamic capacity is reduced by 1/3 which brings it to 133kg (293lbs). Assume you have the full size Rhino Rack as I do, which they say is 41lbs with the backbones system.

Off-road Roof Limit = 293lbs
Rhino-Rack w/ Backbone = 41lbs

Actual Off-road Capacity = 252lbs

Bush Company Awning = 61lbs
MaxTrax (2) and mounting hardware = 18lbs
Light Bar and Mounting hardware = 12lbs
Solar Panel = 6lbs

That leaves me with: 153lbs of off-road carrying capacity on the roof. Not bad, but certainly not enough to carry most RTTs with anything attached to them.


This seems like a problem. Anyone have any thoughts about this? My specific example not withstanding.

Edited to fix a metric conversion.

"The best estimate I have found for the dynamic (on-road) roof carrying capacity of the 200 series is 200kg (440lbs), important to note this is not the capacity of the bars, but the roof itself so far as I can find."

I always thought the Owner's Manual was quite clear that 154 lb (70 kg) was the max allowable for any load on the roof:

RoofCapw.jpg


Any aftermarket roof rack installed that weighs more than the stock roof rack would subtract from the allowable 154 lb (70 kg).

I know that's not a lot, and not a popular number for those with a lot of weight up there, but please show me where Toyota says more than this is OK under any circumstances.

HTH
 
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I'll start this thread with a video that got me thinking about roof load limits. All I have ever seen or looked at are static vs dynamic limits, but it seems the dynamic limits should be broken out into two separate numbers: On-Road vs Off-Road. Take a look at the whiteboard portion of this video and then lets do some math.




The best estimate I have found for the dynamic (on-road) roof carrying capacity of the 200 series is 200kg (440lbs), important to note this is not the capacity of the bars, but the roof itself so far as I can find.

Assuming this video is correct, so just for illustration purposes, lets say that off-road that dynamic capacity is reduced by 1/3 which brings it to 133kg (293lbs). Assume you have the full size Rhino Rack as I do, which they say is 41lbs with the backbones system.

Off-road Roof Limit = 293lbs
Rhino-Rack w/ Backbone = 41lbs

Actual Off-road Capacity = 252lbs

Bush Company Awning = 61lbs
MaxTrax (2) and mounting hardware = 18lbs
Light Bar and Mounting hardware = 12lbs
Solar Panel = 6lbs

That leaves me with: 153lbs of off-road carrying capacity on the roof. Not bad, but certainly not enough to carry most RTTs with anything attached to them.


This seems like a problem. Anyone have any thoughts about this? My specific example not withstanding.

Edited to fix a metric conversion.
Are you sure about the weight of your rhino rack platform? What size are you running? That is one of the main reasons I decided not to put up a rhino platform on my backbone rails.....I purchased size 84 x 56 and that platform weighs roughly 70lbs. I decided just to mount the heavy duty rhino crossbars and mount my RTT to that instead. Big weight savings obviously.
 

TheGrrrrr

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Are you sure about the weight of your rhino rack platform? What size are you running? That is one of the main reasons I decided not to put up a rhino platform on my backbone rails.....I purchased size 84 x 56 and that platform weighs roughly 70lbs. I decided just to mount the heavy duty rhino crossbars and mount my RTT to that instead. Big weight savings obviously.

the rhino rack website load calculator says it weighs 41, I never weighed it and don’t remember how it felt.
 
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"The best estimate I have found for the dynamic (on-road) roof carrying capacity of the 200 series is 200kg (440lbs), important to note this is not the capacity of the bars, but the roof itself so far as I can find."

I always thought the Owner's Manual was quite clear that 154 lb (70 kg) was the max allowable for any load on the roof:

View attachment 2582964

Any aftermarket roof rack installed that weighs more than the stock roof rack would subtract from the allowable 154 lb (70 kg).

I know that's not a lot, and not a popular number for those with a lot of weight up there, but please show me where Toyota says more than this is OK under any circumstances.

HTH

For what it’s worth, I had an AluCab and their 270 degree awning mounted on three RhinoRack crossbars, bouncing around off road without any issues at all. Combined weight was easily over 250lbs.

I only ran this setup for a few months, but even so, if the roof couldn’t handle it, problems would have shown themselves pretty quickly.
 

grinchy

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I think the roof is strong enough, and the rack is strong enough. they’re ripping out the sheet metal. So more feet or more backing material. A proper install is would probably take down the headliner, install a strip of aluminum or steel under the channel with some rivets to hold it in place, then drill this and put bolts up through the reinforcement and the sheet metal for the mounting feet. A pita for sure, but done right.

even The ‘clips‘ we have on the 200 are obviously providing a lot more tear through resistance than the rivets are able to.

Ronny isn’t solving the problem by switching to a new rack unless that rack features a better tear through anchor to the roof than a few rivets.
 

gaijin

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That 154lb metric is for the factory cross bars, not the roof itself.
Are you sure? My reading of the first part of that OM entry leads me to believe that it is not just for the factory cross bars:

RoofCapw2.jpg


I think we might all agree that the factory roof rails, those that run longitudinally down both sides of the roof, are at least as strong as any aftermarket mounting system. And the phrase "two or more" leads me to conclude that even if a robust system of cross rails, or even a platform, would not increase the 154 lb (70 kg) limit.

Just my USD 0.02.

HTH
 

HSTexan

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I think the roof is strong enough, and the rack is strong enough. they’re ripping out the sheet metal. So more feet or more backing material. A proper install is would probably take down the headliner, install a strip of aluminum or steel under the channel with some rivets to hold it in place, then drill this and put bolts up through the reinforcement and the sheet metal for the mounting feet. A pita for sure, but done right.

even The ‘clips‘ we have on the 200 are obviously providing a lot more tear through resistance than the rivets are able to.

Ronny isn’t solving the problem by switching to a new rack unless that rack features a better tear through anchor to the roof than a few rivets.
This is my general feeling as well--I'm no engineer so I don't want to start guesstimating the proper formula for off-road capacity while using an aftermarket rack. I don't think there is one general formula for every vehicle/rack combination and I certainly think it's more complicated than subtracting 1/3.

The biggest takeaway for me with the one failure by Tyler and then Ronny's pro-active repair are both due to rivets required for install. Since I really started my deep dive into this hobby I have not once ever heard of anyone with a roof rack failure who has a bolt on rack into the factory mounts (across 4Runner/LC owners as well as anyone I've met or come across). Perhaps I'm lucky, but this just hasn't been a trend I've ever heard of or seen before. I'm not saying it's not possible, but I do believe if this was an issue with non-riveted racks we would see failures a lot more commonly.
 

sdnative

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Just an thought. Apparently, (according to the video, I have not located the source), Rhino Rack wants you to derate the load carrying capacity of their rack by 1/3 when using off-road. In the video he derated the vehicle load limit as well, but I'm not sure that is correct. I believe the vehicle load limit is valid regardless if on-road or off-road. So only the aftermarket rack rating would need to be de-rated.

So as an example, say the Hilux roof load limit is 75kg and the rack load limit is 100kg. If the rack load capacity needs to be derated by 1/3 for off-road, you would have 66kg. Taking the lesser of the two capacities you would have 66kg, not 50kg as mentioned in the video.

EDIT: at 12:13 it shows the vehicle capacity also derated but I'm not sure that's needed.

I have not verified this so don't take this as fact.
 
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"The best estimate I have found for the dynamic (on-road) roof carrying capacity of the 200 series is 200kg (440lbs), important to note this is not the capacity of the bars, but the roof itself so far as I can find."

I always thought the Owner's Manual was quite clear that 154 lb (70 kg) was the max allowable for any load on the roof

"Do not exceed 154lb cargo weight on the roof luggage carrier".

Toyota engineers have determined the maximum safe weight for use with the Toyota roof rack is 154#. It does not mean that the roof with a different rack could not hold more safely, only that the factory rack has a 154# limit. That said you are correct they do not specify another maximum roof load limit in the owners manual.

I know I've seen a brochure for the 200 series from 2007 or 2008 that was out of Australia which said it had a 200kg limit; however a few minutes of searching this morning and I can't find it. Lots of Australian rack manufacturers will cite the 200kg (440lb) limit of the 200-series, but there's no reference to where they all get it. I did notice that Rhino rack says 330# on-road, 220# off-road for their rack so they are derating 66%, not 75% like the video shows. IIRC the 440# limit is actually NOT evenly distributed on the roof, it's for the rails which the LC feet mount onto

I have a few assumptions I'll share about this. These are all inferences, not actually backed up by Toyota docs:

  • Rhino says 330# on-road load with their full rack. They also use 3 pairs of feet, like the factory rack. I suspect the 440# limit means you need to use 4 pairs
  • Rhino says 220# with 2 of their cross-bars. I'm not sure 4 bars gives you 440# but the math scales. Their doc (below) says 3-4 bars supports 264#, and that it's tested to Australian crash standards. Unsure if 264# is an Australian crash standard or legal limit, or just where they stopped trying.
  • They show a static load rating of 794#!
My one reference for the above. Rhino-Rack Toyota Land Cruiser Brochure 2015 - https://issuu.com/rhinorack/docs/z181_land_cruiser_brochure_issuu

All that said I personally wouldn't want to run 330# (or more) on my roof on-road or off, if for no other reason than dynamic handling.
 
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Some observations looking at the vids
- The Rhino Rack failures in question in the vids are specific to those applications and mounts being particularly susceptible to dynamic loads. Particularly tensile loads (pulling out). Rivets in unsupported sheet metal don't have enough structural margin. I don't believe any of racks on the 200-series use anything but the stock bolt through mounting points embedded in the much more substantial drip rail with stock backing plates. A configuration that's going to have orders of magnitude more robustness than rivets.
- Number of feet as linuxgod points out. LX OEM rack only has 2 attachment points. LC, 3. Some rack like the Prinsu I believe use all 4 mounts on each rail (total of 8). That's going to make a huge difference to what loads a rack can handle.

That said, I would still caution overloading at the top. COG is greatly effected changing handling, safety, and rollover.
 

grinchy

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Watched the vid of the guy who lost a rivited rack from pull thru. His replacement rack is surprise: drill and bolt from below with mounting strips on back side. Uses the rain gutter which is much thicker material.
 
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Some observations looking at the vids
- The Rhino Rack failures in question in the vids are specific to those applications and mounts being particularly susceptible to dynamic loads. Particularly tensile loads (pulling out). Rivets in unsupported sheet metal don't have enough structural margin. I don't believe any of racks on the 200-series use anything but the stock bolt through mounting points embedded in the much more substantial drip rail with stock backing plates. A configuration that's going to have orders of magnitude more robustness than rivets.
- Number of feet as linuxgod points out. LX OEM rack only has 2 attachment points. LC, 3. Some rack like the Prinsu I believe use all 4 mounts on each rail (total of 8). That's going to make a huge difference to what loads a rack can handle.

That said, I would still caution overloading at the top. COG is greatly effected changing handling, safety, and rollover.

This is spot on. I have the full sized ARB roof rack with mesh bottom and side rails. It is bolted down in 6 places with 12 bolts. I forget but I think I had to pop out 2 covers for the extra 2 points of connection. I think the factory rack mounted at 4 points, two in the front 2 in the back? But its bolted down to an SUV roof. Not a pick up truck roof attached to basically sheet metal. Could I overload the rack and make it top heavy and more prone to roll over? Absolutely. But if that thing actually came off its not going to be because it was overloaded and its going to take the roof with it.
 

WCDAVE

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Are you sure? My reading of the first part of that OM entry leads me to believe that it is not just for the factory cross bars:

View attachment 2583073

I think we might all agree that the factory roof rails, those that run longitudinally down both sides of the roof, are at least as strong as any aftermarket mounting system. And the phrase "two or more" leads me to conclude that even if a robust system of cross rails, or even a platform, would not increase the 154 lb (70 kg) limit.

Just my USD 0.02.

HTH
Screen Shot 2021-02-13 at 3.00.47 PM.png


I am not a metallurgical engineer, but I would argue that a set-up like this is much stronger than the factory rails. This partially installed Dissent rack will of course be further reinforced with the double folded (3-plane) side/longitudinal rails bolted thereto and has the open box beams crossing the vehicle. By effectively tying all eight anchor points together you would greatly reduce the tear-out risk and have an increased load capacity over the factory rails. Having said all of that, the roof is the worst place to add weight from an aerodynamic, COG, and ease of use perspective. I'm sure Ronny would agree that the Land Cruiser has a more robust configuration than the Hilux.
 
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I think what we need is Toyota documentation on the actually ROOF load limit.. the rest can be calculated (based on a x1.5 off road calc..or less if you prefer the .66 calc) I have seen the 200kg limit just trying find it since its widely quoted.. there is no difference in the roofs of US and ROW (rest of world) specs that I know of.

The US manual is for the US Specific roof rack (not just the cross bars but the entire rack)
 

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