15" wheels are the original size. The 14" didn't appear on Chevrolet & Pontiac until 1957.
I can't state this as a fact but I have been told in 57 they came in both 14 & 15.
Vern I do not mean to be contentious but it was a Big Deal in 57 when they went to 14" and the model specs for 57 Canadian Pontiacs says:
Sorry no option for 15", 57 was 14" only. Canadian and American.
Although since the car in question was sold with 14" (as was my 56, much modified over the years) one has to wonder, why did they make the drums so small and the wheels so large, eh?
And I put 15" wheels on my 66 Chevelle (factory delivered with 14" only) over the years, as long as the bolt pattern fits and the wheels clear the brakes, seems to me like it is personal choice, eh?
(Carl1 I know you are watching so give me extra credit for the ehs, eh?)
Dave
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1956 Pontiac Pathfinder 2dr sedan, 496 - dyno'd 545 hp, stick shift, 4.11 posi - Hot Rod