There are several differences between an analog tire pressure gauge and a digital model. Digital tire gauges use pressure transducers to display the reading on a screen. They are calibrated with software, making them very precise. Digital pressure gauges require a power source: batteries or solar-powered gauges are the most common. Analog tire gauges feature a needle that points to the numbers on a scale to provide the pressure reading. They are inexpensive, easy to use, and don't require a power source. Analog tire pressure gauges must be recalibrated often for accuracy.