looks like some kind of spare tire bracket
made by stone mfg. co Chicago
says 3 in
any ideas, Bob
A search indicates the Stone Mfg. in Chicago has manufactured apparel since 1932. They also invented a labor saving device for the sewing machines they used in their operation. This may be a machine part that was used in manufacturing apparel. Jim Patrick
It might be a duplexer that will allow you to hang two demountable rims/tires on one spare tire carrier.
Stone-Thompson was a spin off of Universal Rim Co. and a manufacturer and wholesaler of demountable rims and parts.
Stone-Thompson Mfg. eventually changed their name to Stone Mfg.
Click on this link to see a period trade journal ad from 1920:
Stone Mfg. also made a kit that allowed you to make your non-demountable Ford wheels demountable at the hub. It included a complete wood wheel to use as a spare. See the ad below.
Now that I look at your brackets again, it is clear to me that it is a duplexer for demountable at the hub wheels.
With one complete wood wheel mounted to the spare tire carrier, a second tire can be mounted adjacent to the wheel. Note the part of each bracket fits under the felloe of the spare wood wheel while the other part of each bracket fit the bead of the extra tire.
I had some demountable at the hub wheels years ago but I sold them.
Click this thread and scroll down to see the wheels and hubs.
Perhaps this will help: