The rim is 10" rim it actually almost 11 It is two pieces could use a front half which is what sets the wheel width. using them on a vintage dragster i only have one and a back half.
Its the early ford wide five pattern 36 37 38 39 used on modifieds and sprint cars dirt and ashphalt 60s into the late 70's
Safety Racing out of Mich. made them for Modifieds/ Late models back in the 70s. Spun Aluminums came along and pretty much put em out of business.
They are getting harder to find with the resurgence of nostalgia circle track cars. Was a time in the 80s you could find wheelbarrow loads of them here in the NE for short money. Try Sargent's Service Center in Rye, NH. Mike wheels and deals in vintage circle track equipment 603-964-8123. We had a couple of sets of these wheels but they went with the sprinter when we sold it. Good luck.
Took some of them to a swap meet back in the late 70s-early 80s. Couldn't hardly give em away. Now, like most all that old stuff, they've probably turned to gold