Supply and demand and wholesale pricing factor into the tire choice. When you order your new car, even today it only says the tire size, not the manufacturer and model. You don't find out until you get it. And my in-laws and I had the same model, same year, same package car bought new but had different tire models. Running year change or substitution I don't know, but to the automaker tires are tires.

Goodyear Polyglas were more expensive than the Firestone Wide Oval, so not used on the base model cars; but on performance cars the extra cost also gave a performance boost.