Which following distance is safe in dry conditions under 45 mph?

• A. 2 seconds
• B. 6 seconds
• C. 4 seconds
• D. 8 seconds

Answer: (C)

The key idea is giving yourself enough time to react and come to a stop if the vehicle in front slows suddenly. In dry conditions at speeds under 45 mph, using a four-second gap provides a reliable cushion for both your reaction time and your braking distance, plus a little margin for small delays in perception or steering adjustments.

To check this, pick a fixed object on the road ahead. Start counting seconds as the front bumper passes that object; you should still be counting to four by the time your vehicle reaches the same spot. If you reach earlier, you’re too close and need to back off a bit.

Four seconds is practical here: shorter gaps can be risky if your reaction time varies or if the leading car brakes more abruptly, while much longer gaps aren’t usually necessary for normal traffic flow in dry conditions at these speeds. In worse weather or higher speeds, you’d increase the following distance accordingly.