Parking a vehicle on an incline presents a unique safety challenge because gravity constantly acts to pull the vehicle downhill. Proper wheel positioning is a simple, yet highly effective, mechanical safeguard against a potential runaway vehicle incident. This procedure is often a mandatory legal requirement and serves as a secondary defense should the vehicle’s primary braking mechanisms fail.
Parking Uphill: The Correct Tire Position
When parking a vehicle on an uphill street with a curb, turn the steering wheel sharply to the left (assuming driving on the right side of the road). This directs the front tires away from the curb and toward the street center, positioning the back of the tire closer to the curb face. This orientation utilizes the curb as a physical block should the vehicle begin to roll backward.
If the parking brake or transmission fails, the vehicle will attempt to roll back down the slope. As the car moves, the rear side of the front tire will immediately contact the curb. This contact arrests the vehicle’s backward momentum, ensuring the curb acts as the final point of mechanical resistance.
Parking Downhill: The Counterpoint
The technique for parking on a downhill incline is the opposite of the uphill method, though it serves the same protective purpose. When facing downhill with a curb present, turn the steering wheel sharply to the right, directing the front tires toward the edge of the roadway. This positioning causes the front of the tire to rest gently against the curb.
This orientation ensures that if the vehicle begins to roll forward down the slope, the front face of the front tire will immediately bind against the vertical face of the curb. The entire weight of the vehicle is then transferred into the curb, halting the rolling motion.
The Core Safety Mechanism: Curb Interaction
The underlying principle connecting both uphill and downhill parking methods is the intentional use of the curb as a mechanical failsafe, transforming it into an improvised wheel chock. This strategy anticipates the direction of force—gravity—and ensures the vehicle’s movement is directed into the stationary barrier. When the wheels are angled correctly, any gravitational pull that initiates a roll will force the tire to contact the curb at an angle that maximizes friction and resistance.
The contact point is designed to be the part of the tire that faces the oncoming movement, causing the tire to jam into the curb rather than hop over it. This angling creates a leveraging effect where the horizontal force of the rolling vehicle is converted into a vertical force against the curb, effectively wedging the tire. This systematic use of the environment provides a layer of physical security independent of the vehicle’s internal components.
This failsafe mechanism is important because the force exerted by a rolling vehicle can far exceed the holding power of a worn parking brake or a transmission’s parking pawl. The curb provides a fixed, immovable point of opposition capable of restraining thousands of pounds of rolling mass.
Essential Safety Steps Beyond Tire Turning
Engaging the Parking Brake
While angling the wheels is an important safeguard, the initial and most reliable step for parking on an incline involves engaging the vehicle’s parking brake firmly. This system, which typically operates on the rear wheels independently of the main hydraulic brakes, is the vehicle’s primary defense against rolling. Drivers should fully engage the brake before shifting into Park or turning off the engine.
Using the Transmission
The transmission also plays a role in securing the vehicle against gravitational forces. For automatic transmissions, the shifter should be placed into the Park position, which engages a small locking pin, or pawl, within the gearbox. Drivers of manual transmission vehicles should place the transmission in first gear when facing uphill or reverse gear when facing downhill, using the compression of the engine as an added restraint.
Parking Without a Curb
A separate procedure applies when parking on an incline where no curb is present, such as on a shoulder or unpaved road. In this scenario, the wheels must be turned sharply toward the side of the road, regardless of whether the vehicle is facing uphill or downhill. The intent here is to ensure that if the vehicle rolls, the tires direct it off the travel lane and toward the shoulder or ditch, away from traffic.