A car jack that slips or fails can crush you instantly. Invest in high-quality jack stands (available at your local big-box hardware store for around $35) to prevent this catastrophe.
Always change a tire on level ground away from traffic, and block a wheel to prevent the vehicle from rolling as it’s jacked up.
Place the Jack
Most drivers are familiar with having to pull over on the side of the road when they have a flat tire, but it’s important to park in an area that gets you out of traffic. Also, look for a level spot rather than one with soft soil that may sink as you jack up the vehicle, which can cause it to become unstable and fall.
Generally, specific spots under the car are designed to support a jack (called “lift points”), most of which are usually indicated in your owner’s manual. It would help to place a chock block behind the wheel you’ll be lifting to prevent it from moving unexpectedly. You can get inexpensive chock blocks at most auto or big box stores.
Position the Jack Stands
If you’re changing a tire or doing any other work underneath your car that requires the vehicle to be on jack stands, first ensure that the parking brake is set and the vehicle is in Park (if automatic trans) or in reverse (manual transmission). Block the other wheels with wheel chocks, large rocks, or wood chunks to prevent the car from rolling off the tire jack.
Then, find the factory jack points and a place for the Jack Stands. Most jack stands have preset locking points that lock into place when the jack is raised to the proper height. They also have fail-safes triggered by some release, usually a handle that releases the support bar’s ratchet teeth.
Raise the Jack
Many automotive tasks – from changing a tire to inspecting brakes – require lifting the vehicle with a jack. Ensure the jack is positioned correctly, the tires are choked, and you have enough room to work underneath the car.
Slowly crank the jack handle, checking to see that it stays centered under the vehicle and does not lean. Listen for sounds as well, like a pop or thud. If either occurs, the jack is shifting out of position.
If you are working on a front-wheel drive vehicle, block the rear tire with a brick or other heavy object (don’t use your spare). This prevents the car from rolling off the jack and possibly hitting you. Jack stands are also a good idea, but they should never be used to replace the jack.
Lower the Jack
Before you lower your car, remove the hub cap (if present) and chock a tire that will remain on the ground (if you’re changing the tires). Putting your transmission in the Park and engaging the parking brake is also a good idea.
Ensure the jack’s release valve is open by turning it counterclockwise and slowly starting to pump. As the hydraulic pressure builds up, the jack will raise the vehicle. When you’ve reached the desired height, place a pair of jack stands at the safe lift point on either end of the axle and center their saddles under the car.
In an ideal situation, you can pull off the road into a spot clear of traffic and solid enough to support your car. If this isn’t possible, you should still get as far away from the traffic flow as possible.
Place the Tires
If you’ve been driving with a flat tire, pull over in a safe, stable spot away from traffic. Get out your jack and put the spare tire on.
Check the vehicle’s owner’s manual for specific instructions on where to position the jack. Most vehicles have designated jack points, spots under the car where a welded-in metal plate allows you to jack up the vehicle without damaging the frame.
It’s also a good idea to place chocks (or other barriers) under the wheels to keep the car from rolling. You can use bricks, cinder blocks, or large stones. You should also put the car in the Park and engage the parking brake. Doing this will prevent your vehicle from moving unexpectedly while working under it.