How to Change a Tire

So you're driving along and the car starts making that awful clunk-clunk-clunk that indicates that your tire's gone flat. Here's what to do.

Turn car off and engage emergency brake. Try to park somewhere safe. Get as far off the road as is reasonable, but make sure the car is level. The emergency break is important. Be safe while you're doing this.

Remove spare tire (donut) and jack from trunk. It might be heavier than you think. Also, if it's an older car, there might be something holding the tire/donut down. If so, it might be rusted, Use those muscles! The jack and the tire iron are likely to be one and the same.

Without lifting the car, loosen the lugnuts on the offending tire. Use the tire iron. If they're stuck and you feel safe doing so, you can stand on the tire iron to try to loosen the lugnuts (make sure you're turning it the right way). Be careful. If it's raining, be very careful not to slip. This might strip the lugnuts, I've been told, but this is how I've had to do it a couple times. Get them loose enough to move with your hand.

Jack the car up until the tire is just barely off the ground. Check your car's manual for where to place the jack if you don't know. If you don't check, then you can damage the car. Don't jack it up before you loosen the lugnuts, then the tire spinning will make this much, much harder. That will allow you to pull the tire off after you get the lugnuts off. They'll come off if you just use your hand this time.

Finish removing the lugnuts, pull the tire off. Again, tires are heavy. Be careful.

Put the spare on. It's pretty much the opposite of putting it back on.
Tighten the lugnuts by hand, then release the jack. You need to tighten them a little before you put the car back down. When the jack is released, the car will lower, so make sure there's nothing in the way.

You can pull the jack out once the car's off of it.

Use the tire iron to tighten the lugnuts. Don't stand on it this time, but make sure they're solid.

Put the bad tire in your trunk. The jack too, while you're at it. It might not fit back in the same place as the spare, if the spare was a donut.

Get somewhere safe, and make plans to repair the tire or buy a new one. It'll depend on how long you drove on it and what it was that made it go flat in the first place.