Wait...I'm confused. You mean those weren't originally designed for hauling tires? That is all I've ever seen them used for. I figured they were like Pitbull stands that some racer designed out of necessity.
I thought they were originally designed as a boat cart. You used them to get your stuff from the car/truck to your boat. Then they folded up to store in the boat.
No. pulled mine off the truck with some stuff in it after a day on the beach (empty cooler, some chairs) . It broke a latch and bent the support underneath. I still have the 3D design ready for a true tire size version with carbon fiber panels...