Breaking the Beads
To remove the tire from the wheel, both of the tire beads need to be unseated from the bead seats on the wheel.  This is called “breaking the beads”.  The bead breaker is located on the right side of the tire changer and is operated by foot pedal.  The tire is rolled in between the bead breaker arm and the padded side of the machine.  The bead breaker blade is placed on the tire bead and slightly off of the wheel lip as to not contact the wheel rim.  The pedal is activated to break the bead away from the wheel.  Keep hands and legs away from moving parts.  The wheel is turned around to break the bead on the other side of the tire.  The tire may be moved to break other areas on the tire until the beads are completely detached from the wheel.

Plastic protectors are used on the bead breaker blade to prevent scratching the wheel as the blade slides by the wheel.
Bead Unseated from Rim on  Motorcycle Tire Changer