Proper width for Roof Rails for Racking

I've been searching for the answer online, but I can't find what I'm looking for. I bought some Rhino Roof rails that I plan to install on my Camper shell. I don't know what is the best width to install them. I know there are various cross bars of various lengths, but is there some kind of factory standard width or best width for strength, etc.?

 

Looks like maybe 54" or less is the right answer, but I'd like to confirm.

 

54" is WAY too wide!!

It varies depending on just what type/brand of topper that you have on your truck. I also just bought some tracks to install on my topper, and will be doing that soon. You want to mount the tracks as far out towards the edge of the topper as possible, but not so far out that they are on that "sloping" edge. Just want to mount them ON the reinforced portion of the top; look inside and you "should" see there is a significant thickness difference in the top. The manufacturers' place some honeycomb reinforcement of about 3/4" on the top portion of the cap to make it stronger for this very purpose of mounting a roof rack. All you have to do is to make certain that you take advantage of that reinforcement, and also mount your tracks as FLAT as possible. Your bars and "towers" will allow you to customize the width to your liking. You can mount 5' wide bars on your tracks if you need to for something like 2 side-by-side kayaks, but I will keep my bars as narrow as possible so they don't hang up on brush and shit when I'm off-road.

I use my roof rack for ladders and my canoe, so my bars will only be 48" wide.

Hope this helps.

 

Thanks! I found this ARE roof basket and it says:

Available sizes: 55" L x 42" W, 55" L x 47" W and 55" L x 52" W.

Then there's a chart for various truck applications https://4are.com/product/ascend/pdfs/Ascend_Application_Chart.pdf
and it says

2001-2004 Tacoma DC XS Ascend 55" x 42"

So I think I'm going to mount them as close to 42" within that reinforced thick area you were talking about. I'll post pics when I'm done.

 

I went out with a measuring tape and took some measurements. Actually the cap roof is only 42" wide. The thick part of the cap actually created a condensation line with the cold night air, and I measured that width at 34". I will probably mount the rails at approximately 32" width.