Roof Rails (not crossbars) Question(s)

Are the roof rails metal, or something else (composite, plastic)?

My understanding is the weight rating is relatively low, but I believe that is based on the crossbars, not the "rails". Can someone confirm that?

I'm trying to ascertain whether the stock rails have enough strength to hold weight, and maybe how much.

I designed and build a roof rack for my Wrangler that would hold well over 600 lbs, maybe closer to 1k. If the Toyota rails will support 600 lbs, I can design and build my own crossbar/rack system. So, what's the weak link?

 

Weakest link is brackets in roof that rack bolts into.

 

Looks like a/m racks bolt to the brackets in the roof...so, how are a/m any stronger?

 

Stronger steel brackets on roof exterior and stronger racks. I have not seen anyone do testing on when the failure point occurs. Dynamic weight is more of a concern for me than static.


https://www.4runners.com/threads/load-bearing-capacity-for-roof.36703/

 

Ok, to make sure, the brackets "in" the roof are the same and it is the mounting of the a/m "rack" to the roof that is different (strong a/m brackets)?

I'm not too concerned about dynamic weight because I'm not carrying much weight up top while driving. A roof top tent for example doesn't weigh much more than the recommended weight for the factory rails/crossbars; however, you put two people and a dog in the tent and the weight triples, or at least goes way up. I think I have a great way to attach a rack or tent to the factory rails, but I'm not sure the factory rails can support the static weight; obviously they can support the, relatively low, dynamic weight.

If the roof rails are of decent material, aluminum or something, I'm sure they can support static weight of 600 lbs., and static weight will have almost all of the weight against the stock mounts/bolts (no side-to-side, dynamic forces to worry about). Think I'll give it a go, unless someone tells me it's stupid...and then I might still try it!

 

Thanks. Exactly what I had in mind.