I can't figure this thing out...wagon hardware? Gambrel hanger?

All I can really find is they made hardware dealing with chains.  Not sure if that helps.........

Looks like it would cradle a large pipe or a post????

Not sure of this at all but I have something similar that was made by the Chicago Tire Lug Company - Mine is heavier metal and has a chain attached - It was used on wooden rim tires to help get traction when hung up in snow, mud, etc. - This one might serve the same purpose - The hooks could hold the chain

I think you might be on the right track with the snow cleat idea....this did come from a huge pile of fixed socket wrenches and mechanics tools from the 1920's-1930's era.

a quick thought? a bracket to hold a spare tire onto the car?