Hy txpete, the original wheel would have been stud piloted. In 1956 Chevrolet converted their entire line to tubeless wheels and tires as standard equipment including the entire truck line. The standard wheel for your size of truck would have been a 22.5" they were available in several widths depending on the tire size. 19.5" wheels I think would look small on your truck, but that is just my opinion. Your truck could have come from the factory with 9 X 22.5 or 10 X 22.5. depending on how it was equipped and what the GVW was. Most truck buyers did not trust tubeless wheels and tires and opted for the extra expense of tube type wheels and tires, hope that helps.
