Car mfg's have almost always recommended way less tire pressure then the tire Mfg's or their vehicles would not ride "Smooth Enough". Bias should always have been 32 P.S.I. (even in '56) as the tire Mfg noted on the tire side wall, and radial tires 35 to 60 P.S.I. depending on the tire style, size, and MFG. I run 35 P.S.I in the Tigerpaw radials on the Bird and have Great handling and a Smooth ride. My guess you would be in the 35 P.S.I. bracket also.

312T85Bird

What?