Tyre bead is a strong and ductile copper/bronze-coated wire covered with rigid rubber that holds a tyre in place on the wheel rim of a vehicle. It is located on the lower most section (in contact with the wheel rim) of a tyre’s sidewall and is tightly sealed to disallow any passage from the inside to the outside. This ensures that the tyre is held in place and not allowed to come off the rim under any circumstance.
In case, the tyre has to be removed from the rim, such as while repairing a puncture, a bead breaker can be used to break the bead to remove the tyre from the rim. While the term may sound like the tyre bead is broken, in reality it is just involves removal of the tyre bead from the groove on the wheel rim. Afterwards, the same tyre can be refitted onto the wheel rim as it hasn’t suffered any damage while removing a tyre from the rim.