Since you asked...
1. Pull the valve stem core out and let air out of tire.
2. Break the bead. This is the hard part without a bead breaker. Using a jack on a car or truck is something I saw my dad do. I always thought it to be dangerous and unwise. To each his own though. It can be dangerous without the proper tools. If you don't have a bead breaker (like me), I have a tractor with a loader on it that I use. I place the tire under the edge of the bucket and then push down. I don't let anyone else put the tire under for me and I don't let anyone else on the tractor when I am doing it. A lot of on and off of the tractor, but I don't want anyone loosing a finger or hand. I also probably wouldn't plan on using the tire after using the bucket edge on it.
3. Once the bead is broken on both sides of the tire, lube the bead of the tire to help it slip off. Push the first edge to the center of the rim and (I use tire spoons) take the spoon and lift the first edge over the rim. Most people get into trouble with the second bite with the second spoon. TAKE A SMALL BITE and levering next to the first spoon, lever the next bit of lip over the rim.
4. Here is the next part that people get in trouble with. The third spoon. Most people only buy two spoons and loose the lip that is already levered part of the tire bead over the rim. I have three spoons. I take the third spoon and take another small bite next to either the first or second spoon and lever the lip over again. Then take the spoon in the CENTER out, and take another small bite next to the spoon on the right or the left.
5. Continue until the tire bead is completely over the rim. Then start on the next bead in the same manner.
Don't let the levers pop back up and smack you in the jaw, groin or ribs. It might hurt. I use my knees to hold the levers down.
Placing air back into tires can sometimes be a real pain. Take the valve core out of the NEW valve stem that you put back in. That will allow more air in to seat the bead. Lube both tire beads first. If you are putting in a tube in the tire, some people like a little air in the tube and some like to put it in flat. Just make sure you don't pinch the tube with your spoons, and deflate it at least once to help get wrinkles out of it once the tire is back on the beads.
Putting a tire back on is basically the reverse. Clean the rim bead up real good before placing another tire on it. I use a wire wheel on a hand grinder, or sandpaper.
And get a bead breaker if you plan to continue doing tires yourself. It's really too much work after a few times.
I don't do tires anymore.
