According to my contact at Nike: several years. (She cautioned me against buying too many pairs at once.) Foams break down. As with food "best by" dates, you c

According to my contact at Nike: several years. (She cautioned me against buying too many pairs at once.) Foams break down. As with food "best by" dates, you can get away with rather a lot more than they recommend. But a quarter-century seems like too much to ask.