On most cars, the numbers along the left-hand side of a tachometer indicate the engine's RPM. This number ranges from 1 (low) to 7,000 (high). The number in the middle of the dial indicates how many times per minute your engine is spinning. The orange area in the middle of the tachometer shows you where you are in relation to the danger zone. When you start to enter this zone, an indicator light on the tachometer will turn from yellow to red.