How to Observe Distance by Checking the Rearview Mirror?
3 Answers
When judging the distance of a car by checking the rearview mirror, a common rule of thumb is: the smaller the following car appears, the safer it is. If the following car occupies 1/3 of the mirror, the distance is about 10 meters. If it occupies 1/2, the distance is about 7 meters. If the following car fills the entire mirror, the distance is about 3 meters, which is not suitable for turning. Below are specific methods for observing distance via the rearview mirror: 1. When checking the rearview mirror: The driver should divide the rearview mirror into "inner" and "outer" sections. Whether it's the left or right rearview mirror, the half closer to the driver is considered the "inner" section, and the half farther away is the "outer" section. This method applies to judging vehicles on either the left or right rear side. 2. Drivers should understand that the closer the following car is, the smaller the visible area of the car will appear, and it will be positioned more toward the outer section of the mirror. Conversely, the farther the following car is, the more complete its visible area will be, and it will appear closer to the inner section. Generally, if the following car is at the boundary between the inner and outer sections of the mirror, the distance is approximately 25 meters. 3. Drivers can also estimate the distance to the following car using the interior rearview mirror: If only the hood of the following car is visible and not the grille, the distance is about 3 meters. If the grille is visible, the distance is around 8 meters. If the entire wheel of the following car is visible, the distance exceeds 20 meters.
When I first started driving, I always had trouble judging distances with the rearview mirrors. A friend taught me to adjust them properly first. The center mirror should be adjusted to show the entire rear window, without making the cars behind appear too small. As for the side mirrors, only a tiny edge of your own car should be visible—this minimizes blind spots. In daily driving, use the mirrors to judge distance by observing the size change of the car behind you—if it rapidly grows larger, it means it's getting closer, so be cautious when changing lanes. When reversing, I also like to use reference points, such as parking lines or curbs, and estimate the gap by checking the mirrors. Beginners should practice in open spaces, like moving around in a parking lot, and gradually get the hang of it. Remember that mirrors have limitations—always turn your head to check blind spots before changing direction to avoid accidents. Pay attention to your reactions at different speeds while driving, and always prioritize safety.
As a veteran driver with decades of experience, judging distances through rearview mirrors isn't actually difficult—the key lies in intuitive adjustments. When I get in the car, I first align the center mirror to the rear, ensuring a clear field of view is enough; I angle the side mirrors slightly downward until the car's shadow almost disappears, which enhances distance perception. How to gauge distance? By observing the size of the following vehicle: if it suddenly appears larger, don't hesitate—wait for it to pass before moving; when changing lanes, it's safe only when the car in the mirror appears smaller. Once you're accustomed to this method, even city traffic jams become manageable, with mirrors serving as your 'second eyes.' With enough road experience, you'll learn that at higher speeds, distances change rapidly—check early, don't wait until they're right on your tail to react. Practice more, and driving will become second nature.
