How to Determine the Distance of the Rear Vehicle Using the Rearview Mirror?
2 Answers
Methods to determine the distance of the rear vehicle using the rearview mirror: 1. The smaller the rear vehicle appears, the safer it is. When the rear vehicle occupies one-third of the mirror, the distance between the two vehicles is 10 meters; 2. When the rear vehicle occupies half of the mirror, the distance is 7 meters; 3. When the rear vehicle fills the entire mirror, the distance is 3 meters, and it is not suitable to turn. When observing the rearview mirror, the driver should divide it 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.
As a driving instructor, I always emphasize that judging distance through rearview mirrors is a fundamental safety skill. With the interior rearview mirror, if the following vehicle covers most of the mirror's surface, it indicates they are too close, likely within 50 meters; if it occupies only a small portion, such as 1/3 of the mirror, the distance is relatively safe. Side mirrors are also crucial—I recommend dividing them into left and right halves: when a vehicle is in the left half, it’s usually over 100 meters away, but when it moves to the right half, it’s getting closer and requires caution. During practical training, observe changes at different speeds—on highways, at higher speeds, the mirror changes more rapidly, making distance perception harder to gauge. Beginners often overlook weather conditions, such as rain or fog, where light reflections can distort distance judgment. In such cases, rely on vision but reduce speed in advance. Developing a habit of checking mirror cleanliness daily improves accuracy. Overall, regular on-road practice is key, as it helps build instinctive reactions within weeks.
