Backspace difference?

Is there a backspace difference between the 14" X 5 1/2" steel wheel vs. the 14" X 4 1/2" steel wheel? It is my understanding the 14" X 5 1/2" steel wheel will have a 3 3/4" backspace. I borrowed an original 6.95-14 wheel/tire from a FABO member and made some measurements.

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My CRUDE measurement tells me the backspace is 3 1/4".

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I'm thinking this is a 4 1/2" wide rim.

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Can anyone confirm if this is a 4 1/2" rim?