The fact that the two wheels are clearly different one measures larger than the other (even if it isn't where proper rim diameter is measured) would be enough evidence for me. to remove the suspected wheel and tire and measure it properly. Better safe than sorry.
Even if it is a 16" rim my sense of symmetry would compel me to remove it and find a rim that matched the other three.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
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