When should you retire those running shoes? The NY Times offers some advice. Most runners use running shoes. There is a small but growing segment that believes running shod (with shoes) is less healthy than running with shoes however, they are in the minority. How many miles is too much? Should you have a few pairs of shoes that you switch between? When are those shoes truly dead? Check out this article, it can provide some helpful advice. By GINA KOLATARyan Hall, one of the world's best distance runners, used to pride himself on wearing his running shoes into nubs. No more. Now he assiduously replaces his shoes after running about 200 miles in them. He goes through two pairs a month. "I know that my shoes could probably handle a couple of hundred more miles before they are worn out, but my health is so important to me that I like to always make sure my equipment is fresh," he said. Of course Mr. Hall, sponsored by Asics, does not have to pay for his shoes. Most of the rest of us do, and at around $100 a pair they aren't cheap. Yet we are warned constantly to replace them often, because running in threadbare shoes may lead to injuries that can take months to heal. So here's a simple question: How do you know when your shoes are ready for those discard bins in gyms? And if you do get injured, is it fair to blame your shoes? My friend Jen Davis runs more than 100 miles a week, like Mr. Hall, but has a different set of criteria for getting rid of shoes. One is that if they smell bad even after she washes them in her washing machine , it's time for a new pair. She estimates she puts 500 miles on each pair of shoes. Henry Klugh, a running coach and manager of The Inside Track, a running store in Harrisburg, Penn., says he goes as far as 2,000 miles in some shoes. He often runs on dirt roads, he said, which are easier on shoes than asphalt is and do not compress and beat up the midsole as much. My coach, Tom Fleming, has his own method. Put one hand in your shoe, and press on the sole with your other hand. If you can feel your fingers pressing through, those shoes are worn out — the cushioning totally compressed or the outer sole worn thin.