25 year old tires are usually as hard as steel rimmed wagon wheels and handle about the same. They are fine but for riding around on, I wouldn't do it.
New temporary spares (donuts) would be a better choice.
Yup, thats why I put a set of quicktimes on it. They were getting dry rotted BAD. Plus the quick times are shorter, so the rear end of the car isint "all jacked up" so to say......