I only bought them because I needed more, they didn't go bad. This system is so easy to use that I've repaired more tires on my friends' cars than mine. Especially now with TPMS systems, a warning often appears shortly after a flat tire. It's much quicker than changing a tire, removing a nail, putting in a plug (repressurizing the tire if necessary) and moving on. Ride a real tire, not that stupid donut. Have your tire professionally patched when you get home at your regular tire dealer. By the