Rooftop Tent Question

[TinyTimmay]

Greetings OB members!

My first post and why not start a thread at the same time? haha

I'm from eastern North Dakota and have grown up car camping, hiking and mountain biking. The last few years I've discovered dispersed camping and have put together a decent setup for "Overlanding".

My brother in law recently bought an iKamper RTT and wanted to use it on his Honda Pilot. He already had a roof rack system in place, but it was clip style and not a more permanent mount. Through some research, and after discussing with a roof rack system company near Minneapolis MN, he decided to get a new roof rack (Yakima) and have it permanently installed at said roof rack company. He told me that he was advised to NOT use a clip style roof rack system when attaching an RTT to it. Has anyone else heard this before?

My current setup is a 2017 Jeep Grand Cherokee Limited, Yakima roof rack (clip style) and a Smittybilt Overlander RTT. I'm on my 3rd season of using this setup and love it! However, I'm curious from a safety standpoint if anyone else has heard the thing about avoiding clip style roof racks when mounting RTTs to them?

Thanks in advance!

 

[OTH Overland]

Most important factor with roof racks is attempting to determine what the actual load rating of the particular rack is. There are three main things needed to determine, Static Load Rating: How much weight will the rack support when parked, i.e. camped and you and all your gear is up there sleeping. Dynamic Load Rating: How much weight is the rack good for when traveling down the road. Needs to be greater than the weight of the tent, what's stored inside, and the rack itself. Then does the rack manufacture apply an 'off highway' dynamic load reduction, where the amount is reduced to account for vibration and impact. Among all this you need to look for the lowest common denominators of the system, mounting method, capacity of the chosen load bars, etc. and finally what does the vehicle manufacture give for allowable roof loads. The world's strongest rack does not do any good if attached to a weak gutter, or factory roof rails that are fastened to the vehicle with sheet metal fasteners. Our Jeep Wrangler has fiberglass top with built in gutters, not something I would put my trust in mounting anything to, however the gutter can be a very strong point on some vehicles, and there are racks that use that mounting point to their advantage. When shopping ask to see some written values for the rack and mounting system limits, and also know how much real weight you will be carrying up there. most tent manufactures exclude their mounting hardware, ladder and accessories from the listed weight of the tent, then add in some bedding and the weight of the rack itself and you would be surprised how much you have up there.

 

[TinyTimmay]

Most important factor with roof racks is attempting to determine what the actual load rating of the particular rack is. There are three main things needed to determine, Static Load Rating: How much weight will the rack support when parked, i.e. camped and you and all your gear is up there sleeping. Dynamic Load Rating: How much weight is the rack good for when traveling down the road. Needs to be greater than the weight of the tent, what's stored inside, and the rack itself. Then does the rack manufacture apply an 'off highway' dynamic load reduction, where the amount is reduced to account for vibration and impact. Among all this you need to look for the lowest common denominators of the system, mounting method, capacity of the chosen load bars, etc. and finally what does the vehicle manufacture give for allowable roof loads. The world's strongest rack does not do any good if attached to a weak gutter, or factory roof rails that are fastened to the vehicle with sheet metal fasteners. Our Jeep Wrangler has fiberglass top with built in gutters, not something I would put my trust in mounting anything to, however the gutter can be a very strong point on some vehicles, and there are racks that use that mounting point to their advantage. When shopping ask to see some written values for the rack and mounting system limits, and also know how much real weight you will be carrying up there. most tent manufactures exclude their mounting hardware, ladder and accessories from the listed weight of the tent, then add in some bedding and the weight of the rack itself and you would be surprised how much you have up there.

Appreciate the response, very helpful!

I'm curious if anyone has been advised to NOT use a clip style roof rack system when mounting an RTT to it?

 

[MazeVX]

Yes that's a common advice. However it's not necessarily true, a proven practice is to increase the number of gutter clamps if possible.
Roof structures are incredibly strong but always try to stay within the manufacturers limits of all components. Check the mounting, screws, clamps whatever regularly and more often when driving on rough terrain and everything should be fine.

 

[rgallant]

If by clip style you mean gutter mount then it is all about the vehicle, not the mount so much. I have LR Discovery II and use gutter mounts, but the gutters on the Disco are metal welded to the body. I still run 3 load bars though.

My Tepui Ayer tent, easy awn swift awning , load bars, and bedding runs 155ish lbs my dynamic load is 160 lbs as far as I have been able to determine. Most trucks dynamic load is 100 to 110 lbs.

The vehicle manufacturers should be able to tell you, but it is like pulling teeth to get the numbers

 

[bear_den_overland]

Look into the static and dynamic load ratings. If you are in spec, I’d use it. :)

 

[TinyTimmay]

If by clip style you mean gutter mount then it is all about the vehicle, not the mount so much. I have LR Discovery II and use gutter mounts, but the gutters on the Disco are metal welded to the body. I still run 3 load bars though.

My Tepui Ayer tent, easy awn swift awning , load bars, and bedding runs 155ish lbs my dynamic load is 160 lbs as far as I have been able to determine. Most trucks dynamic load is 100 to 110 lbs.

The vehicle manufacturers should be able to tell you, but it is like pulling teeth to get the numbers

I have the Yakima Baseline roof rack currently, and they have "BaseClips" which hook onto the top of the door jams. This system is designed for naked roofs. While my 2017 Jeep Grand Cherokee has roof rails, when I searched Yakima and their roof rack products, this is the system that was recommended I use and the roof rails are not at all utilized in this setup. My RTT is 118lbs if I remember correctly, and the only thing I have added to it is a 2" memory foam mattress (queen size maybe?) from Walmart and a bed sheet, and those two items stay folded up inside the RTT while I travel. Add in the weight of my roof rack and I still think I'm below 160lbs (which seems to be a common load rating weight that others have mentioned). Now, as an aside, I also have a Yakima awning that I have had on there as well. Now that added weight could be putting me in a bit more of dicey situation and I could certainly live without it in the field. The RTT offers a bit of shade/rain protection when opened and could be enough for me when the need arises.

I've been running this setup for about 3-4 years and haven't had any issues at all with it. Nothing seems to work itself loose even if I'm in rugged country. I'm leaning towards continued use with it and not get inside my head too much about it.

 

[rgallant]

@TinyTimmay One thing I found recently is that the dynamic load is not totally engineering, safety regulations tend to reduce it for rollover concerns. So Land Rover UK used to rate Defenders and Discoverys at 150 KG about 330 lbs, but the EU and North America halved that to 75kg or 150 to 160 for "Safety Concerns".

But your awning unless it is a big 270 will only add 20 to 30 lbs. The big thing is to be aware your Center of Gravity is higher, so don't drive it like a ow slung sports car.

 

[TinyTimmay]

@TinyTimmay One thing I found recently is that the dynamic load is not totally engineering, safety regulations tend to reduce it for rollover concerns. So Land Rover UK used to rate Defenders and Discoverys at 150 KG about 330 lbs, but the EU and North America halved that to 75kg or 150 to 160 for "Safety Concerns".

But your awning unless it is a big 270 will only add 20 to 30 lbs. The big thing is to be aware your Center of Gravity is higher, so don't drive it like a ow slung sports car.

Appreciate the suggestion!

 

[MidOH]

You can add a 3rd crossbar (or 4th) to strengthen it. That's what we did with mountain bikes and kayaks. (I refuse to drive less than 80mph)

Otherwise, yeah, I'm adding through bolts and triangulation.

 

[rgallant]

@MidOH That does not resolve the dynamic load issue. Dynamic load has more to do with COG change, there is a whole formula but it is ridiculously complex, as it factors in cog height change , suspension stiffness , tire stiffness, wheel base length and width and a bunch of other stuff.

 

[TinyTimmay]

@MidOH That does not resolve the dynamic load issue. Dynamic load has more to do with COG change, there is a whole formula but it is ridiculously complex, as it factors in cog height change , suspension stiffness , tire stiffness, wheel base length and width and a bunch of other stuff.

And doesn't specifically apply to my situation either, the additional crossbar recommendation. I have the Yakima Baseline system with mount points at each door so 4 total. To add more mount points and crossbars does not seem like a resolution.

I think I'm gonna be ok with my current setup, and will continue to drive slow and carefully as to avoid any unnecessary sharp turns and tipping over. I'm rarely in a hurry when I'm out on adventures and gladly let people go around me when they're in a rush.

 

[rgallant]

@TinyTimmay I did some reading Yakima says 165 Lbs so if you are under that you are fine. I finally found the answer to why they do not recommend it on Thule's site

hule Tepui rooftop tents SHOULD NOT be mounted to any type of roof rack system that clamps into the door of the car, including Thule Traverse and Thule Evo Clamp systems. The high static weight of the tent may cause damage to the roof.

So the concern is your roof getting deformed, so if you put a big tent and add say 2 adults and 2 young children the static load may cause damage where the mount rests on the roof. Functionally denting the roof. I suspect this is a largely cover our ass situation as they would have to test every vehicle to see where damage could occur.

If you have had no issues then you are good, just keep an eye on mounts but after 3 season if you have no damage I doubt you will.

 

[TinyTimmay]

@TinyTimmay I did some reading Yakima says 165 Lbs so if you are under that you are fine. I finally found the answer to why they do not recommend it on Thule's site


So the concern is your roof getting deformed, so if you put a big tent and add say 2 adults and 2 young children the static load may cause damage where the mount rests on the roof. Functionally denting the roof. I suspect this is a largely cover our ass situation as they would have to test every vehicle to see where damage could occur.

If you have had no issues then you are good, just keep an eye on mounts but after 3 season if you have no damage I doubt you will.

Appreciate the response! I'm usually solo in my 118lb Smittybuilt Overlander RTT so, like you said, I haven't had any issues with static load up to this point so probably okay with continued use.

Thanks!

 

[genocache]

Hi Tim, I don't know what mounting features there are for your Jeep. I made a custom roof rack for my 1960 Land Rover out of Super Strut and for the clamps I used ones from Gamviti ; Rain Gutter Towers — Gamiviti They also make roof channel towers; Roof Channel Towers — Gamiviti. I have no financial stake in the company.

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[rgallant]

@genocache Good suggestion but he has no gutters, his mounts have a "hook" that grabs the door frame then a soft rubber/abs support on the roof. They work really well, but have a small contact area on the roof.

 

[Sea Diamond]

Here is a rack concept that has worked well for us...bouncing over some pretty rough terrain.

The ladders come down to the body combing and supports the aft end of the rack...and the bulk of our weight while in the tent. The front of the rack is captured on the gutter...but I have dispersed the load with 4 hard rubber blocks glued into position. These blocks are over the interior roll bar and has no problem relieving the stress that is put on the FRP gutter.

Hope this helps.