Just completed Midwest Offroad Expeditions' "Wendigo Watch 2025" this past weekend, and had to 37s strapped into my bed, and they didn't move an inch I also have been on many Silver Lake Sand Dunes trips, with no problems there either. I too like running a tonneau cover, along with using my bed often for dirtbikes, and just hauling stuff in general. I took a piece of 1/4" steel, and traced part of the circumference of the tire onto it, ground it off, and then, used angle iron, and welded it to the plate. I then drilled holes through the bed, bolted it down, and voila. It works well.
Now, after some note taking, and running this setup for a little over a year now, I have come up with a better, sleeker design.
I will be throwing that chunk of steel that I made away, and instead of the angle iron on top of the steel, I am going to get some flat bar and bend it to match the shape of the tire, then weld that directly to the plate. I will be then flipping it around, keeping the same strap orientation, but also then removing the tie down point, and welding a tie down point to the bed support. This way the tires are further towards the rear of the truck more, and will be held tight against the "mount" on one side, and the bed support on the other. Hope my DIY experience helps!
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