Don't forget the Firestone 500. The 500 was for how many miles you would get out of that tire.
I know someone that was running these tires on his '69 Riviera. They would wear funny, have bubbles in the sidewalls, etc. Hit a pothole and the tire would get egg shaped.
It was not a problem getting new ones at the Firestone store. The problem was you'd just keep getting more of the same lousy tires.
Fortunately for my mom, the Firestone store also sold Michelins, so she finally got put into a set of Michelins since it was probably cheaper for them to give her 4 of those instead of continuing to mount new 500's every other week.