There is more to a tire than just the tread and the air inside. Tires stay on your rims from the pressure of the air inside on the bead against the rim. The bead is the "rolled" edge of the tire. Even without being inflated, the bead can still be firmly sealed to the rim. You can take your tire to a tire shop and pay to have it remove the bead, or you can make a bead breaker out of a few simple materials. You can efficiently replace a worn tire or swap out your rims without extra expense.
Let the air completely out of the tire by removing the screw cap from the air valve and pressing the centre pin in. Hold the pin in to release the air.
Measure and cut three pieces from one 8-foot two-by-four: a 12-inch piece and two 24-inch pieces.
Locate one of the jack lift points on the underside rail of your car's frame. Consult your owner's manual to find these, or you can look under the car near the front of the driver's side door or toward the rear of the passenger door. The jack lifting points are pre-moulded indentations in the rail that are meant to receive the lifting head of the jack.
Lay the two 24-inch pieces on the ground, wide side down, 3 feet away from the car. Place the tire you will be removing from the rim on top of them so the middle of the tire is in line with the lifting point you located on the car. The rubber of the tire should be fully supported on the wood so the tire lays evenly on the wood and no part of the rim touches the ground. Check to make sure that the tire is stable and does not rock when you press on one side of the tire. Adjust the wood pieces so the tire is well-supported.
Place an 8-foot two-by-four so one end is under the car and the wood runs in line with the lifting point and is over the centre of the tire.
Lift the end of the 8-foot piece of wood that is over the tire up into the air. Slide the 1-foot piece of wood you cut between the 8-foot piece and the bed of the tire. The smaller piece of wood will be at a slight angle.
Press down on the end of the 8-foot piece of wood as if it were a jack handle. The end under the car will press against the lifting point, and the pressure put on the 1-foot piece of wood will break the seal of the bead against the rim.
Place a large flat screwdriver between the bead of the tire and the rim and release the pressure on the wood. This will prevent the bead from falling back into place and resealing.
Remove the short piece of wood. Turn the tire. Set the short piece between the "handle" and the bead and repeat the process to break the bead. Insert a second flathead screwdriver where the bead breaks next. Push down on the handle of the first screwdriver to pop that section of bead over the rim and remove that screwdriver. Do this all the way around the tire, breaking the bead and moving the screwdrivers, until the bead is completely free or the rim.
Rub the seam between the rim and the bead with a few drops of liquid dish soap. This will lubricate the rubber and make it easier to separate from the rim.
Many new cars come with tires equipped with inflation sensors. If you do not reinstall the sensors as per the manufacturer's instructions, you may get an error code and the sensors will not work.