In most cases, your shoes will begin to wear out within 3 - 6 months. However, other factors such as the quality of materials and build and how often you wear them also determine how quickly you replace the shoes. Signs that indicate your walking shoes need replacing include worn-out outsoles where the treads are even, or the heel is more worn out on one side than the other. Wrinkles on the sides or bottom of the sole are indications that the midsole cushioning is worn out and is not providing support.