63-was the beginning of a few changes in tires, including the short lived experience with Rayon cord tires.
New cars were arriving on dealer lots with 2 ply/4ply rating tires and salesmen were using a rock and patches of fabric to demonstrate how 2 ply was better. I can close my eyes and still see Harry the salesman demonstrating the superior flex of 2 plys over 4.
I also remember Harry finding a way to put 4 ply Firestones on the new Chevelle Mom was in love with because he really wanted to sell the car..
Rayon went away, Nylon came in and next thing we got glass belted tires with wide footprints that stuck to the pavement. Then we got steel belted radials.