Newton Running shoes wear like car tires: from the outside in. Like wear on car tires, shoe wear is a result of friction: the shoe sliding along the ground during your gait cycle. This is like a car skidding to halt or spinning its wheels taking off from a stoplight. When you run, this may be so slight you can’t hear it, but the wear on your shoes shows where you are creating friction. If the heel of your shoe shows wear, you are braking on the foot strike. This is inefficient and you should increase your forward lean. Make sure you maintain good posture (lean from the ball of your foot, not your waist).

As the wear on your lugs accumulates, you will see that the front third wears significantly more than the rear two thirds. This is totally normal, and to be anticipated.  Ideally, the four lugs will wear evenly, with wear distributed between all four.

If you have excessive wear in the area in front of the lugs (under your toes), you are toeing off at the end of the foot strike, and pushing harder off the ground than need be. This is also inefficient and indicates that you are not utilizing the benefits of the shoe’s forefoot technology. Remember to lift from the hip flexor, rather than pushing off with the foot.

Retire your shoes when any part of the shoe is worn down unevenly about ½ an inch more than the surrounding material. An example would be one side of the four protruding lugs under the ball of the foot is worn down. If you wear the shoe evenly, it will continue to perform even if you wear down all of the rubber lugs. This is because the Action/Reaction Technology™ continues to work regardless of wear.

The number of miles you can get from a pair of Newton Running shoes depends many factors, the most important of which is the efficiency of your gait. In most cases you will get the same type of mileage out of your Newton Running shoes that you have had in traditional running shoes. Highly efficient runners will see more mileage.

If you don't track your mileage, you can base your need for new Newton Running shoes on how they feel – when you feel like your Newtons are no longer giving you the same "pop" they once were, it's time for a replacement.