Last month I got a flat and changed my first tire. Fortunately, it was in my kitchen! I inspected the tires on my bike, as it was used, and decided it would be a good idea to go new. So, I ordered Conti GP4000s from Amazon and they arrived yesterday. Tonight I changed out my tires. So, when I have a flat on the road (it is inevitable, right?) and need to do a roadside repair, I can at least take comfort in the knowledge that I have successfully changed 3 tires.