Tire Gauge to Avoid Over-Inflation I just purchased a tire floor pump with a gauge for my bike. The gauge seems to start off at 0 PSI when I connect the pump to the tire. So, do I need to use a separate tire gauge to first measure the current pressure of my tires prior to using the pump so as not to over-inflate them?

Additional info: I purchased the Serfas TCPG Bicycle Floor Pump and the gauge does not move at all when the hose is attached until I start pumping. Not sure if that's correct or if I'm doing something wrong.
The pressure dial doesn't measure the pressure in the tube - it gives the pressure in the entire system (tube + hose).  When you connect your pump, you need to pressurize the hose to the same level as the tube before it will read anything.  I usually find this takes two or three full pumps, and the resistance jumps up massively once the tube and tire have the same pressure. At that point, the dial will show you the pressure in your tire.