Perhaps this wasn't common back then, however, clincher or "wire-on" tires could be "folded" down like a bandsaw blade. Typically into three loops. It could also have to been because the older wire beads were heavier and less flexible than the tires of the later 70's and early 80's before Kevlar beads.

Hey, Jim. If anyone would be an expert on this it is you. As a machinist, cyclist frame builder, tourist and hanging out with Mike Sinard and the company that was innovating tires at the time. If they could fold (or loop) back then, you would have done it. So, what was different? Or was this just a bad practice that some tourist, bike catalog companies and idiots like me did? Keep in mind that I didn't keep it pretzeled up for a month.

Sorry for the tangent. The racks look great Jim. And they look to be handling a lot of weight.