Car basics · Some practice · about 20 to 30 minutes
Change a Flat Tire
A flat tire can happen to anyone. If you're somewhere safe, you can put on the spare with the tools that came with your car. Practice once in your driveway so you're not learning on the side of the road.
When to teach it: Watch from about 8, help from about 12 by handing tools and loosening lug nuts, and do it alone around the time they're learning to drive.
You'll need
- Spare tire
- The jack and lug wrench that came with your car
- Owner's manual
- Wheel wedges, if you have them
- Tire pressure gauge
- Gloves and a flashlight
Before you start
- Get to a safe spot, like a parking lot, side street, or wide shoulder, on solid, level ground away from traffic.
- Turn on your hazard lights.
- Put the car in Park, set the parking brake, and turn off the engine.
- Get everyone out of the car and away from traffic. No one should stay inside a car that's being jacked up.
- If changing the tire would put you or your passengers at risk, don't do it. Call roadside assistance instead.
Step by step
Tick each step as you go if you like; ticks stay on this device.
Physics
How it works: Levers, torque, and the jack
A lug wrench is a lever. Torque is the turning force you create, and it equals how hard you push times how far your hand is from the nut. Push with 50 pounds at the end of a 1-foot handle and you make 50 pound-feet of torque. Push the same 50 pounds on a 2-foot handle and you make 100 pound-feet.
That's why you push near the end of the handle. It's also why you loosen the nuts while the tire is still on the ground. If the wheel were in the air, it would just spin. On the ground, the tire's grip on the road holds it still, so your torque goes into the nut.
A car jack trades distance for force. You crank the handle around many times, moving your hand a long way, and the car rises only a little. If you ignore friction, the work you put in equals the work you get out, so a small push over a long distance can lift a heavy load a short distance. This is called mechanical advantage.
torque = force × lever arm; load force × distance lifted = effort force × distance moved (ignoring friction)
Try it: Open a heavy door by pushing right next to the hinges. Then push near the handle. The handle side is much easier because the lever arm is longer, so the same push makes more torque.
Keep learning: Science
Teaching it to your kids
- Practice in the driveway on a nice day, with an adult handling the jack.
- Let your child loosen and tighten lug nuts while the car is on the ground.
- Have them draw the star pattern for your car's number of lug nuts before you start.
- Find the jack points together, first in the manual and then on the car.
Tips
- Check your spare's pressure when you check your other tires.
- Lefty-loosey: turn lug nuts counterclockwise to loosen them.
- Keep gloves and a flashlight with your spare.
- A temporary spare isn't made to last. Get your regular tire fixed or replaced soon.
- With practice, the whole job takes about 20 minutes.
Common mistakes
| Mistake | Instead |
|---|---|
| Jacking up the car before loosening the lug nuts | Loosen them a quarter to half turn while the tire is on the ground. |
| Putting the jack under a plastic panel | Use the jack point shown in your manual, on the metal frame. |
| Tightening the nuts in a circle | Use a star pattern so the wheel sits evenly against the hub. |
| Driving fast or far on a compact spare | Follow the speed and distance limits on the spare or in your manual. |
Safe habits
- Never put any part of your body under a car held up only by a jack.
- Use only the jack that came with your car, at the jack points in the manual.
- Block the wheel diagonally opposite the flat.
- Keep everyone out of the car and away from traffic while you work.
When to call a pro
- If you're on a busy highway or don't feel safe, stay away from traffic and call roadside assistance.
- Lug nuts need to be tightened to a set amount listed in your manual. If you don't have a torque wrench, have a tire shop check them as soon as possible.
- If a wheel stud or lug nut looks damaged, have a shop fix it. Damaged studs may not hold the wheel on.
Sources
Free how-to guides for families, with nothing to earn, pass or send in. They follow U.S. rules and sources; your owner's manual, product labels and state and local rules come first.