CA Pub Res Code Section 42865

(a)

It is the policy of the state that until a state tire recycling program is fully underway and operational, the shredding of used tires shall be encouraged.

(b)

For the purposes of this act, a “tire” refers to any vehicle tire whose major component is rubber, and its component parts. “Shredding” includes both mechanical and cryogenic shredding which reduces tires to a size of less than four inches in width.