Final answer:
When parking downhill with a curb, turn the front wheels towards the curb. When parking downhill without a curb, turn the front wheels away from the curb.
Step-by-step explanation:
When parking downhill with a curb, the front wheels of a car should be turned towards the curb. This is done to prevent the car from rolling into the street if the brakes fail. The front wheels should be turned away from the curb when parking downhill without a curb, allowing the car to roll away from the curb in case it starts to roll.