annual demand is reduced for new, virgin
tire material.
The ARA reported that the retreading
process gave new life to almost 30.25
million tires in 1993. This was down
somewhat from the 31.5 million tires and
31 million tires in 1991 and 1992,
respectively.  Of the 1993 total, 6.6
million (22%) were passenger car tires,
down from 8.5 million in 1991; 7.35
million (24%) were light-truck tires
(almost even with 1991); and 15.4
million (51 %) were medium truck tires,
up from the 15 million 2 years before.
In the smaller markets of off-the-road
vehicles and specialty tires, 0.66 million
and 0.22 million retreads were produced,
respectively (together, 3 % of the market).
ARA reported that the recent drops in
passenger car retread production was
mostly the result of highly competitive
(low) retail pricing of new tires and a
gradual increase in consumer interest in
expensive, high performance, and the
relatively new 70,000- and 80,000-mile
premium tires. Fueling lower tire prices
was the increasing entrance of wholesale
clubs and discount chains into a relatively
flat, new tire replacement market. This
market for passenger tires decreased
slightly in 1993, primarily because of
strong sales of new automobiles.
Continuing gradual growth in the
production of medium truck retreads was
encouraged because of the high
replacement cost that makes retreading
more cost effective.33
Technology.-A significant, source
reduction-related technology has been the
longer-wearing  vehicle  tire.  The
development of the radial tire more than
a decade ago increased the tread life
expectancy from the range of 20,000 to
25,000 miles, for the standard bias-ply
tire, to 40,000 miles and more for the
then new  radial-ply tire.  An added
advantage of the radial tire was that it
delivered better fuel mileage. A trend to
smaller cars began somewhat earlier,
during the 1970's. Smaller cars usually
use smaller tires. These factors caused a
reduction in the amount of rubber used in
the manufacture of tires and,
consequently, in the quantities of tire


waste generated. According to a World
Rubber & Tire Report issued in 1992 by
the Freedonia Group of Cleveland, OH,
the amount of natural and synthetic
rubber used in tires dropped from 45 % of
all rubber consumed in 1980 to 42% in
1990.   The International Institute of
Synthetic Rubber Producers in Houston,
TX, estimated that almost 52% of all
synthetic rubber currently consumed goes
into tire production.  Both of these
percentages could change further during
the next decade if the most recent
advanced tire technology is significantly
integrated into the tire marketplace. In
1991, the original producer of the radial
tire introduced a new radial tire in the
United States that it warranted for 80,000
miles. Although the new technology has
not been fully revealed by the
manufacturer, these tires include the use
of a newly developed family of
elastomers.34
Raw material markets are being
affected by the mix of raw materials used
in the radial tire.  Radial tire design
produces higher operating temperatures
than that of other types of tires, and this
affects the composition of the tire
material.  The higher temperatures
perpetuated an increase in the percent of
natural rubber needed. Synthetic rubber
helps tire tread last longer, but natural
rubber is less heat sensitive. Radial-ply
tires are composed of about 16% natural
rubber as compared to their bias-ply
predecessors that used  11%  natural
rubber.  Thus a small yet significant
portion of synthetic rubber, which is
manufactured from nonrenewable
hydrocarbon resources, is being replaced
with natural rubber, a renewable
resource.
Two   companies   claim  to  have
developed tire pyrolysis technologies
which are economically feasible. Up to
now, pyrolysis generally has not been
viable.  Too small a portion of the
byproducts-pyrolytic oil, gas, char, and
metal from the char-have been profitably
marketable on a consistent basis. The gas
is usually used to fuel the process, and
the metal, approximately 1.1 kilograms
(2.5 lbs) of the typical 9-kilogram (20-lb)
tire, is clean enough to market. But the


grade of pyrolytic oil and char is often
below market standards. Both companies
claim that their more sophisticated
pyrolysis technologies produce higher
quality materials. One of the proposed
processes operates at a relatively low
temperature, 1770 to 2050 C (3500 to
4000 F), as opposed to the traditional
operations at 9250 to 9800 C (1,7000 to
1,8000 F). The char or 'carbon black" is
sold to manufacturers of low-grade
carbon products, such as hoses and tires
for lawn mowers and forklifts. Thus far,
pyrolysis technologies have not been able
to produce a carbon black of high enough
grade to reuse in tire production.35 But
even if low-temperature methods prove to
be successful, widespread commercializa-
tion of them appears likely to be several
years away.
Since 1990, the STMC reports that one
significant technological change has
occurred in the tire-to-energy industry.
In the second of the two commercial
facilities in the United States, certain
innovations have allowed for whole tires,
as well as processed TDF, to be
combusted, thereby lowering everyday
operational expenses.
Markets and Prces.-Continued
growth is projected for most scrap rubber
markets. But the two market areas that
offer the most potential are incineration
as a fuel and for energy generation, and
the use of crumb rubber in the
maintenance and rebuilding of highways.
Most of the current uses are expanding
and some, such as cement kilns and
utility plants, are limited principally by
reliable tire supply.  However, the
expansion of these uses would require
significant capital outlay for plant
modifications needed to use TDF or
whole tire fuel.
Depending on final revisions to the
ISTEA legislation, originally passed in
December 1991, the use for scrap tires
could grow significantly through 1997
because, as originally written, the law
mandated a recycled content of rubber
material on federally funded State roads.
Beginning in 1994, 5% of all federally
funded roads paved with asphalt was to
contain recycled scrap tire rubber at the


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