Also consider off set. You want zero if the wheels are stock.
Matching the 4 wheel dimensions with the other 3 will more important than anything else. If the other 3 are non-stock dimensions (and alike to each other) at least match the 4th to the other 3.
Or make sure all 4 wheels match the originally equipped dimensions.
15X7 6 hole wheels with zero offset and a 2600 # load capacity.
Given the picture above I would seriously question the integrity of that wheel.
1966 Mercury Park Lane 4 DR Breezeway 410 4V, C-6, 2.80 - Streamless.
1966 Lincoln 4 door Convertible 462 4V 1971 Ford LTD Convertible 429 4V Phoenix ~ Yeah it's hot however it's a dry heat!