Now that tire age is moot, I have a story:
Nine years ago, when I got my 73, it came with good looking tires, so I left them because there were other things to fix. In a few months, the car was reliable enough to drive across town to a friends restaurant for lunch. Upon leaving the restaurant, I noticed the rear passenger tire was flat. Burst at the sidewall. I got into the trunk and pulled out the donut, and put it on. Although when I squeezed it, it felt fine but it was flat due to a rotted valve stem. The tire was HARD!
Remembering that I had roadside assistance and free towing, I called for a tow to get to the tire shop, only a mile and a half away.
When the tire shop associate came out, I pointed to my flat Road Hugger Radial GTs, and said "I want to replace these with the same tire".
He said "I can't do that". It seems they didn't make them any more. My tires were 18 years old!
I've been running on Cooper Cobras since.