tires

[Glenn Thoreson]

Firestones use polyester cord. The other bias ply tires, per my research, use nylon. Nylon tires get flat spots when sitting. It can take quite a few miles to run the flat spots out, depending on the temperature. If you're only going 20 or 30 MPH you may, or may not notice it. I'm very sensitive to vibration and I won't use a Nylon tire.
As a note of little interest, tire mileage in the day was usually expected to be in the 10K range. Some makers boasted 15K. I doubt both statements.