dddd

I would say based on experience that tires, as they age, become ever less suitable for anything near full inflation pressure, and that the tread becomes faster wearing.

The bond between plies, under the tread where the plies overlap, weakens with age, even if stored in a sealed package. This affects the tire's ability to contain high pressure without suffering "outer-ply failure", or loss of tension in the outermost ply. This becomes apparent when the centerline of the tread appears S-shaped and where some bulging is apparent.

Perhaps not always the case, but I've had new-looking, aged tires wear out within a few hundred miles.

And as greatscott mentioned, the tread surface can become shiny, squeeky and slippery, requiring a serious scrubbing-in before they feel safe.

As a lighter rider, running far below maximum pressures, I probably get away with what others shouldn't try.