Quote: 20 + years old,5,700 miles,no rot,look like new,pitch them ??
Yes! Unless you have jacked the car up so the weight has been off the tires most of their lives, they have been sitting in the exact positions for long periods of time have flat spotted. Each of those long term siting flat spots have deformed the belts inside the tires. Then you take those tires out on the road, and after a few miles, they return round and smooth out, but the damage is still there. Your highway speed ride creates a lot of heat which will compound the defective belt situation. I suspect you have been fortunate for the last 8- 10 years. Are you still feeling lucky?
Your tires would probably be great for a trailer queen that hides in a trailer, comes out to park on the field, do a little low speed around town driving, then go back in the trailer. To expect 20 year old tires that spend most of their lives sitting in the same place holding up a car, to go out and do highway speeds is pretty brave.
Personally, I would be changing those tires if it was my car. Gene
