I've always been told that when you come to a red light or stop sign, to stop far enough behind the car in front of you so that you can see the bottom of their back tires. While a good general rule, I was wondering what would happen if, while you were following this rule, a much larger/speeding vehicle rear-ends you, causing you to hit the car ahead. Would the size/power difference be taken into account as to who's at fault for hitting who? I'm not looking for specific ratios, only if it matters. A bonus would be how much weather is taken into consideration.

Currently in CO, but do find myself getting out quite a bit.

1 Answer 1


There are only two rules I am aware of that apply to rear-end collisions on a roadway (in which all vehicles are properly headed in the same direction):

  1. The first vehicle that hits another in the rear is at fault for the collision, and any collateral collisions.
  2. The preceding rule is always true unless there is evidence that the vehicle that was struck did something reckless or intentional to cause the collision. For example, "cutting" in front of a truck and decelerating unnecessarily and faster than the truck can brake. (Before dashcams became widespread this was a common tactic of fraudsters, who would subsequently sue the "rear-ender's" insurance company for "whiplash" injuries.)

You seem to be asking whether there is a law or rule against coming to a stop too close to a vehicle in front. Tailgating is generally illegal, but I have never heard of the concept being applied to vehicles that are not moving.

(Clarification on your question: "Stop far enough behind the car in front of you so that you can see the bottom of their back tires" is a safety heuristic that allows you to pull around the vehicle in an emergency without shifting into reverse. It's a "rule" of defensive driving, but I have never heard it written into law.)

  • 1
    I've always been told that if you hit someone after you've been hit you were at fault for not keeping a safe enough distance from the car in front of you. Commented Feb 13, 2017 at 15:22
  • 3
    @SonOfSam: As you point out in your question, that would not be a usable rule because the question of how far you move when hit from behind is primarily a function of the velocity and relative mass of the vehicle that hits you (and secondarily of vehicle construction). The rule to leave enough room to see where the vehicle's tires in front of you hit the road is a safety heuristic to ensure that you can pull around them in an emergency without having to shift into reverse.
    – feetwet
    Commented Feb 13, 2017 at 16:54
  • I would think the rule should also apply in some cases the front vehicle moved in a way that could not have reasonably been foreseen by the one behind, regardless of whether such action was a result of intention or recklessness on the part of the person driving the first vehicle that was struck from behind. For example, if car #1 pulls out of a driveway directly in front of car #2, which collides with it, and car #3 hits car #2, I would not fault #3.
    – supercat
    Commented Jan 20, 2021 at 16:04
  • @supercat – what I described as "rule #2" can account for that, although in that scenario car #3 could still be faulted for a failure to maintain a "safe following distance" if it was "tailgating" car #2.
    – feetwet
    Commented Jan 20, 2021 at 17:06
  • @feetwet: A safe following distance is generally regarded as being sufficient distance that one would be able to stop behind the front vehicle even if it were to do the fastest possible controlled stop. Perhaps the first rule should clarify that if a vehicle is hit in the rear "without either vehicle's motion having been substantially affected by immediately-preceding collisions...". Most common scenarios involving rear-end collisions start with a rear-end collision, but in situations that don't I don't think rule #1 should be considered inapplicable.
    – supercat
    Commented Jan 20, 2021 at 17:24

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