A tire chopping apparatus includes a rotor assembly with a plurality of circumferentially and axially spaced rotor teeth which cooperate with a plurality of stationary teeth supported on a shear bar assembly to shearingly engage tire carcasses to reduce the carcasses to smaller fragments. A plurality of axially spaced guards extend outwardly from the shear bar assembly toward the rotor assembly and limit the size of fragments which can pass through a shear zone formed by the interengaging rotary and stationary teeth. The guards may be in the form of bridge plates spanning the rotor assembly or upstanding guard plates which extend upwardly from the shear bar assembly and include a distal end which extends outwardly toward and in horizontally spaced relation to the rotor mandrel.