Lexus GX 470 - Roof rails vs Cross bars

[overl4nd]

I see a lot of people attaching cross bars to their Roof rails (Factory rails) and then attaching tents and stuff to the cross bars.
The cross bars are on the rails, so indirectly the weight is on the roof rails. So I have a question, why not directly mount the Roof top tents to the roof rails instead of getting cross bars and attaching tents and stuff to those?

 

[McDuff123]

One could, I suppose...
However, I see 2 advantages to mounting an RTT to crossbars...
First, it increases the vertical distance off the roof. You’ll want some space there so that you can get you hands in to fasten/unfasten your mounting mechanism.
Second, it’s easier to be able to slide your roof mounting points left and right to integrate into the bottom of the tent. If you used the rails, your roof mounting points could slide fore and aft, but that’s less useful as the
tents mounting points maybe more fixed.

I had our tent mounted on 4 stock crossbars before I went with a Prinsu rack. Worked fine...
BTW, my stock crossbars are available for cheap if anybody needs. Rails too.

 

[overl4nd]

Thanks for your answer. So convenience and asthetics aside, from a safety point of view, Roof rails should be fine?

 

[FirstToy]

I believe the oem rack is only rated to 130-lbs or so. Actual weight capacity minus lawyer filter is maybe 2x that?

Personally, I think you're on the right track.
I would not use the factory rack for anything more than light duty work. It's actually called a "luggage rack"
If you take the end caps off, the rack brackets don't inspire a lot of confidence for frequent hd use.

 

[Btdub1]

So do aftermarket roof racks mount into the roof where the factory rails are mounted? I know there are rain gutter mounts for some racks but I wasn’t sure how they hook up to the GX

 

[McDuff123]

Aftermarket racks (I’m only familiar with the Prinsu that I installed, but I’m assuming they all mount the same) use the same mounting pads (3 per side) on your roof. I think the additional strength comes from the stronger rails and more crossbars that the aftermarket racks use, but they’re still limited by the stock mounting pads.
I’ve not had any problems with my 170 lb RTT, on either the Prinsu, nor the stock bars. I did add 2 extra stock bars when I ran it that way, to spread the load from 2 bars to 4.

 

[overl4nd]

I believe the oem rack is only rated to 130-lbs or so. Actual weight capacity minus lawyer filter is maybe 2x that?

Personally, I think you're on the right track.
I would not use the factory rack for anything more than light duty work. It's actually called a "luggage rack"
If you take the end caps off, the rack brackets don't inspire a lot of confidence for frequent hd use.

Thanks for this! This means installing cross bars and then mounting to them is also not safe I guess

 

[FirstToy]

With the roof rack, I really think some thought about load safety is warranted. Only because offroading does put a lot of dynamic load onto the roof rack cargo.

It's easy to get carried away in scaring people but just be sensible and you'll be alright. If you take the plastic covers off the OEM rack, you can get a good idea of how strong it is.
If I were putting a rtt on the oem rack, I would leave the plastic caps off so inspection of the rack would be quick and easy.

I've seen rooftop tents mounted to OEM racks, so I don't think it's dangerous per se. Offroading adds a lot more dynamic stress than someone who is using one on a Highlander or CRV. The downsides of rack failure, while low, are quite serious. It deserves some consideration if you are putting a heavy load up there.

Just pay attention to the load rating and go with what you feel comfortable with.

Thanks for this! This means installing cross bars and then mounting to them is also not safe I guess

 

[overl4nd]

Thanks. So if the tent is lighter than 130lbs we should be good as it’s lower than load rating

what about sleeping.Static load of 500lbs or so?