I got these to keep in my car for off road use after not defating my tires and had 2 flat tires. I changed tires and decided to try these. After reading the guide a few times, I decided to try it on one of my new tires. It didn't "pop" like the instructions say, but it was capable of deflating the tires to 20psi. It doesn't go any further or they fall apart. I'll see if I'm happy with them after a trip in a few weeks.