Classic 1966 GMC Pickup Tires-White-wall?

I am having my father's 1966 GMC flairside pickup restored. We are almost done, and I have a question about tires. Does anyone know if the original truck would have had white-wall tires, or black-wall tires. I have the original off-white wheels and the white "dog dish" hub caps. I'm concerned that white-wall tires would just be a little too much white. This particular truck has the spare tire mounted just aft of the cab on the driver's side. I'm planning to purchase the tires during the first week of May. Thanks in advance for your thoughts.

I don't remember w/w being an option or seeing them in those days. I have seen them on trucks at shows though.

IMO white walls would be too much white, as you say.

I have some Popular Mechanics magazines from the mid '60's which show some advertisements for well - optioned pick ups (ie: they have full size wheel covers) with white walls.

However, dog dish hub caps were the basic standard format and would not have come with white walls from the factory.