Final answer:
When parking, a vehicle must typically be at least 15 feet away from a fire hydrant, which is about one car-length, to ensure access for emergency services.
Step-by-step explanation:
When parking near a fire hydrant, the distance you must keep clear varies depending on local laws. However, a common rule of thumb is that you should park no closer than 15 feet from a fire hydrant. This regulation ensures that fire trucks and emergency responders have clear and immediate access to fire hydrants in case of a fire emergency. In terms of car lengths, since the average car is about 15 to 16 feet long, this would roughly translate to one car-length away.