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 a 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 work on your form. Make sure you maintain good posture and position (lean from your ankle; don’t bend at 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 lugs will wear evenly, from one side to the other.
If you have excessive wear on the front of the shoe (under your toes), you are toeing off too hard 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 midfoot technology.
It is not uncommon that some runners will burn off the outside (lateral) lug. This doesn’t mean you are supinating – in fact, most runners with this wear pattern are pronating. It indicates you are hitting the ground to the outside of your foot with a slight stabbing motion. To correct this, try to bring your foot back toward you as it strikes the ground.
Retire your shoes when any part of the shoe is worn down unevenly close to the surrounding material. An example would be one side of the lugs under the ball of the foot is worn down level to the outer part of the outsole. 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/ReactionTM technology continues to work regardless of wear.
The number of miles you can get from a pair of Newton Running shoes depends on 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.
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 Newton shoes are no longer giving you the same "pop" they once were, it's time for a replacement.