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TABLE 6.12
Estimated Total Scrap Tire Market for 1998

Market Quantity (millions of tires)
Fuel 114
Cement kilns 38
Pulp or paper mills 20
Dedicated tires to energy 16
Electric utilities 25
Industrial boilers 15
Civil engineering 20
Products 23
Ground rubber 15
Cut, punched or stamped 8
Miscellaneous and agriculture 5.5
Export 15
Subtotal 117.5
Total generation of waste tires 270

Source: Scrap Tire Management Council, 1999. Reproduced with kind permission of the Scrap Tire Management Council.

6.14.4 CRUMB RUBBER
For several recycling processes, tires are shredded to a fine particle size (about 5 5 cm or 2 2
in.) for eventual processing. The steel is removed magnetically and the particles are often shredded
a second time to produce crumb rubber. The remaining rubber is treated to restore its ability to bond
with other materials. Recovered rubber can then be combined with virgin rubber or other materials
to produce a quality product.
More than 227 million kg (500 million lb) of crumb rubber is used in North America in one year
and the rubber manufacturing industry used more than half this amount. Uses for crumb rubber
include fillers in rubber compounds and asphalt modifiers, for example athletic tracks. Rubber adds
flexibility to the surface, better traction, and increases the lifetime of the material (Rhyner et al.,
1995; Kohrell, 1993). However, there are many other applications for recovered crumb rubber
(Table 6.13). Manufacturers can achieve substantial savings in material costs. Improved mixing and
curing properties are additional benefits that result from the use of crumb rubber.

6.14.5 RETREADED TIRES
Approximately 26.2 million retreaded tires were sold in the United States and Canada in 2000, with
the following breakdown (Tire Retread Information Bureau):

● 6.3 million light truck tires
● 18.2 million medium-and heavy-duty truck tires
● 750,000 other tires (aircraft, off-road vehicles, industrial or lift trucks, motorcycles, farm
equipment, and specialty uses)
● 1.5 million passenger car tires

Table 6.14 lists various industries using retreaded tires.
U.S. and Canadian retread tire industries used approximately 260 million kg (575 million lb)
of tread rubber in 2000. There are approximately 1200 retreading plants in North America, a large