This device applies immense concentrated pressure to the sidewall of a tire just above the rim flange. The force pushes the stiff steel or aramid bead bundle out of the wheel's safety hump, breaking the airtight seal. On tire machines, it is a heavy metal shoe powered by a pneumatic cylinder located on the side of the unit.
Heard on the job
Watch your fingers when you actuate the bead breaker, that cylinder has enough force to crush bone.
Related terms
Alloy wheel
A vehicle wheel cast or forged from a mixture of aluminum or magnesium.
Run-flat
A tire designed with reinforced sidewalls to continue operating safely for a limited distance after losing air pressure.
Split rim
A multi-piece heavy-duty wheel assembly designed to lock a tire bead in place using a removable outer ring.