Abstract: A secondary waste apparatus for shearing waste material such as a discarded vehicle tire which has already been reduced in size by a primary shearing process. The apparatus includes a pair of counter-rotating shafts, each shaft having a plurality of generally annular shear members extending in a unitary construction from an abutting relationship with the shaft to an outside diameter which meshes with the shear members of the other shaft. The ratio of the diameter of each shaft to the maximum radial extent of the shear members abutting the shaft being greater than 3:5. Adjacent shear members on a shaft are spaced apart by a driving spacer and one or more grind-depreciable shims. Waste material from a primary shearing process is fed into the apparatus to further reduce the maximum size of the material. The apparatus is periodically sharpened by grinding of the shear members and the shims.