They date from either 1997 or 1987 -- back then the date code did not specify what decade. They do have plenty of tread, in fact they look like new tires (apart from the fact that they are falling apart).
I did look at the tires and thought them okay for test drives but didn't see the severe damage as it only appears in a short section of tread -- possibly the section that was on the ground for the past 16 or 26 years (the car had been off the road for a long time).