Help to ID 6 lug wheels

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Hi Guys, I'm getting ready to restore my uncles old race car trailer and i'm trying to ID the rims that are on it. I'd like to get rid of the two split rims and put regular one piece rims in their place with a set of the Chevrolet dome hubcaps. They are 15" six lug and are only about 6" wide (haven't broke one down yet for an exact measurement. From looking around, I have seen similar wheels on Chevy cars and trucks from the 40's and early 50's. There were a couple of nice sets for sale locally, but they are 16" rims. Any idea what the 15" x 6" non-split rims came on? Any help would be appreciated.