Physics of Dynamic vs Stationary weight

[JMyerz]

Seems to be a lengthy debate without much evidence on can I mount a RTT on a canopy. Just found this article and thought it might be useful, while I can't comment on the accuracy of this equation it is interesting, maybe someone can verify this persons math?

http://outbackjoe.com/macho-divertissement/macho-articles/roof-loading-and-roof-top-tents/

 

[stingray1300]

Personally, I think he's done the "hammer-to-the-head" test a few too many times... :sombrero:
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My RTT is 200#. SnugTop rates their cap at 200# Dynamic load (moving). Static load (stopped, sleeping in the RTT) is somewhere is the range of 600# (RTT included). Thule rack rated at 750#.
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2 years yields no issues (no stress cracking, even in the paint).
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Just drive the dam_ thing!

 

[Pilotamis]

What Thule rack do you have that's rated for 750#?

 

[JMyerz]

FWIW I just talked to Brian at ARE and their Fiberglass caps are rated with a dynamic load rating of 150lb and they test the static to above 800lbs and they haven't heard of anyone having issues with putting a tent and people up there.

 

[Lemsteraak]

If you check with both Thule and Yakima, their racks are dynamically rated at a maximum of 165#, and some applications are much lower

What exactly does that mean?

Short answer - you are on your own if you load more than that on their bars. Their bars are stronger than that. Thule for example rates their bars dynamically at something like 212# in Europe but the same bars are rated at 165# for the US market.

I think OutbackJoe is correct, I like his thinking because he is doing just that, thinking. Use these ratings as a guideline as every vehicle is different. If you load 200# on the roof of a Hummer, fine, but that same load would be ridiculous on a little Sammy. So, a general discussion is really ridiculous, you need specifics to make a guess as to what is safe. Do your own math.