rubber soles in shoes gets harder over time?
Recently I was having this conversation with a friend. I like to stock tennis shoes whenever I find a good deal. He disagreed, saying that rubber soles in shoes get harder over time, and therefore it might not be a good idea to stock shoes for a long time, because it cannot be good for your knees.
Since we're both no experts in shoes, I'm wondering if anyone know if that's a fact or just a myth?
Wilson Kobra Tour, Wilson BLX Six.One 95, Babolat Propulse 2