The size of tire shreds, provided by the California Integrated Waste Management Board (CIWMB), ranged from about 30 cm long by 5 cm wide by 0.8 cm thick (long and thin) to about 10 cm long by 5 cm wide by 5 cm thick (massive rubber) to about 3 cm long by 2 cm wide by 0.8 cm thick (chips). A trace of tire crumbs (2 to 5 mm size) was also noted. These dimensions are typical of routine tire shredding operations. The specific gravity of the tire shreds was determined to be about 1.20. The variation in porosity from loosest to densest was estimated as 0.68 to 0.49.