Recap; (wikipedia) or retread is a previously worn tire which has gone through a remanufacturing process designed to extend its useful service life. Retreads are significantly cheaper. As a result, they are widely used in large-scale operations and they are also the most environmentally friendly way of recycling used tires.
These babies of mine are on their twilight. Adizero, the oldest, came in 2008. She holds most of my personal records (fastest time) in my running, from 5km to 42km. She's the cream of the crop. The Lunarglide and the Boston both came in 2009, successively. The former was the one responsible for my ultramarathon training. She helped me rack mileage after mileage in my preparation for the bdm 102km race. She was the severely shredded unit among them. The Boston, who came after the Lunarglide, helped me in several training runs and fast races. She significantly propelled me to a milo elimination qualifying race in 2010. The Launch, the youngest of them all, is the most sought, most used trainer and racer as of today. With two full marathons and a 50km ultramarathon distance under her soles, she still rocks, and is the one in tip-top shape.
Although all of them had their own retreading, they still have their own competitive means. They still posses their own characteristics and are still the favorites. I don't usually retire my running shoes, they still have their place in the cabinet and are just a call away. I'm positive they could still lead me to the finish line despite their condition.
In some applications, a tire can be retreaded ten times. The process of retreading requires, after the buffing off of the old tread, there to be coated with another compound like rubber to allow the new tread to adhere to the used tire casing. At the end of life, retreads may delaminate and fall apart in chunks that scatter across the road.
If you notice the retread failure along the road, it may be me (who do not notice it) just ahead of you. As long as the loss of a retread does not severely impair my motion control or usability, I will still be running above a recapped sole.
How about you?