Tires are flexible and they give. When you put air into them, they swell up as the pressure builds. The swelling also slows down the build up of pressure.
PVC is not flexible. Maybe using an air hose from a filling station is not such a good idea. The results could be explosive if the pressure builds up too fast. I think I'll use a bicycle pump to put air into my Playsport Pressure Tester. I should be able to get to 3 ATM and not kill myself with PVC shrapnel.