Kansas DMV Practice Test

When conditions are not ideal, you need more distance to stop safely because traction is reduced and braking takes longer. The four-second rule gives a reliable buffer for perception, reaction, and braking so you won’t collide with the vehicle ahead if they brake suddenly or if you encounter a slick patch.

To apply it, pick a fixed object on the road ahead. As the vehicle in front passes that object, start counting seconds. If you reach the object before you’ve counted to four, you’re too close and should slow or ease back to create a four-second gap. If weather or visibility is particularly poor, you should maintain even more than four seconds, especially at higher speeds or behind large vehicles. This extra space helps absorb sudden stops and accounts for longer stopping distances on wet, icy, or snowy roads.