A method for using an ultrasonic thickness gauge to assess outsole wear in running shoes

The purpose of this study was to develop a method to quantify the wear rate of outsole rubber in the lateral heel strike area of running shoes over 350 miles. Sixty-two (62) male runners participated in a 350 mile accelerated running shoe study in which the thickness of the outsole rubber in 1 pair of shoes was measured non-destructively at approximately 10 mile intervals. Outsole rubber thickness was measured using an ultrasonic thickness gauge at 4 points on the heel. Total wear rate was calculated at each successive interval as the total thickness of rubber lost divided by the accumulated miles. The results showed that the wear rate started at 0.034 mm/mile and then decreased towards a plateau of 0.010 mm/mile as the shoe approached 350 miles.