Changing a tire is something driver should know how to do. Every driver is going to experience this some time and should know how to change there tire.
When you first pull off the road look for a flat spot or a turn out to park at putting the emergency break on. Make sure the ground isn't too soft. Locate which tire needs changing and take the jack, spare tire, and tire iron out. Jack up the corner of the car that has the flat tire. Place the jack under the axle or A arm. Make sure the jack is on a level spot on the ground and is not going to sink or slip. If the jack is too tall scrape the ground down till the jack will fit. Make sure the jack is not going to damage a part of the A arm and wont slip out. Jack up the tire until it is just above the ground. Remove the wheel cap and loosen the lug nuts using the tire iron. Place the lug nuts somewhere they are not going to get dirty or lost. Remove the tire and place it where your spare is usually kept.
To put the new tire back on place the tire next to the car and lift it up so the holes in the wheel line up with the lugs on the axle. Push the tire on and hold it while you hand screw on the lug nuts. Make sure the lug nuts go on a couple turn without too much effort to ensure it is not cross threaded. Use the tire iron and tighten one of the lug nuts snug. Next tighten the lug nut opposite the first one until snug. Then go to one of the lug nuts next to the first and tighten it snug. Continue this pattern until all the lug nuts are snug. If this is done write this will create a star pattern. Once all of them are snug tighten the lug nuts as tight as you can without too much effort.
After this is done replace the wheel cap and let the jack down and remove it. Put the jack back in the vehicle and make sure you didn't leave anything else and you can then be on your way.
