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Publications archive - Waste and recycling

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Key departmental publications, e.g. annual reports, budget papers and program guidelines are available in our online archive.

Much of the material listed on these archived web pages has been superseded, or served a particular purpose at a particular time. It may contain references to activities or policies that have no current application. Many archived documents may link to web pages that have moved or no longer exist, or may refer to other documents that are no longer available.

A National Approach to Waste Tyres

Commonwealth Department of Environment, 2001

8 Practices for Managing Waste Tyres

This section provides an overview of the methods that are available to manage waste tyres. The term practices in the heading refers to the actual (physical or engineering) processes that waste tyres undergo (including disposal to landfill); that is, the term relates to the technology employed. The term option in this report is reserved for activities under the general umbrella of policies, strategies and frameworks that might be considered by governments or industry to promote a greater uptake of certain practices.

8.1 The waste management hierarchy

A concept that has been adopted widely to assist in assessing and prioritising practices for dealing with waste is the waste management hierarchy. The waste management hierarchy provides a framework within which different practices for managing waste are listed in order of preference. A commonly used form of the waste management hierarchy is given below:

Eliminate

Reduce

Reuse

Recycle

Dispose

For the purpose of the discussion in this report, the waste management hierarchy has been adapted as follows in accordance with other authors in this area38.

Avoid

Reuse

Recycle

Waste to energy

Dispose

The concept of the waste management hierarchy should be considered as providing broad guidance only and the ordering above is not intended to convey a preference for individual waste tyre management practices. This study takes the position that decisions need to be made on the results of soundly based assessments of individual practices on a case by case basis taking into consideration option-specific factors. Some of the issues that may need to be considered have been discussed in Section 6.

Currently, by far the most widely used practice is disposal to landfill (as well as illegal dumping), followed by retreading (which can be considered a form of reuse) and waste to energy. Aside from disposal, waste to energy is the only option that provides an immediate large-scale solution.

8.2 General operational requirements

Before discussing individual practices for the end-point or fate of a waste tyre, it is worthwhile to review the major activities that are an integral part of the management chain for a waste tyre to arrive at whatever end-point.

8.2.1 Collection, transport and storage

Collection, transport and (where appropriate) intermediate storage are very significant components in the management of waste tyres. Regardless of the ultimate fate of a waste tyre, arrangements have to be put in place for its collection and transport. The costs, difficulties and other factors associated with this part of the waste tyre chain have a direct bearing on the opportunities and viability for the various use, processing and disposal practices that may be considered. It is also noted that this stage of the waste management chain is perhaps the most critical in terms of the level of illegal or inappropriate disposal.

It is worth observing at this point that not all waste tyres are ‘generated’ at tyre retail outlets. Operators of large fleets may obtain their tyres through wholesalers and make their own arrangements for the disposal of waste tyres generated by their operations. A fleet owner who contracts for the disposal of waste tyres directly with a tyre collector assumes much the same role as the tyre dealer in the more common situation. Conversely, a fleet owner who manages waste tyres directly become in effect the tyre collector (in the case of disposal to a remote site) or receival facility (in the case of on-site management). In either case, it would appear that there are no special issues from a regulatory or policy point of view. However, the economies of scale and other considerations may open up opportunities for innovative management solutions. In any case, advice from the trucking industry is that the aggregate number of waste tyres managed directly by the tyre owner is likely to be small in relation to the totals for a State or Territory.

Pick-up costs are largely independent of the ultimate fate of waste tyres, so are not likely to influence decisions as to which management practices to adopt. Transport costs, on the other hand, effectively define a catchment region for a particular waste tyre receival facility. The magnitude of transport costs for tyres generated outside the catchment preclude transport to the facility on a commercial basis, depending on the gate fee/payment at the receival facility. On the other hand, pickup and transport costs are usually quoted as one price, and market considerations may result in some cross subsidisation in cases where a contractor offers a discount to secure business.

8.2.2 Shredding

For this report, the term shredding is defined as the processing of the tyre into more useable shapes or sizes but does not generally involve separation of the material components (rubber, steel, fabric). Shredding is also taken to include cutting of large (typically OTR) tyres into manageable sections using hydraulic ‘jaws’ (similar to those used for scrap steel cutting) and guillotines. The distinction between shredding and crumbing (discussed below) is somewhat blurred particularly, for larger crumb particle sizes.

A wide variety of different types of shredding equipment is available including locally manufactured and overseas equipment. Mobile units have been developed but the extent of their use in Australia is uncertain, although apparently limited. The primary application of shredding in Australia appears to be for volume reduction prior to landfill. Some shredded rubber is used in products such as ‘soft fall’ in playgrounds.

The technology and experience in operation of shredding equipment is well established and there continues to be further development to produce equipment with improved operational and economic characteristics. Capital costs for a shredder capable of processing around 250,000 tyres per year are reported to be of the order of $0.5 to $1 million. Reported costs for shredding tyres vary, perhaps due to differences in the specification for the end product, but appear to fall in the range $0.40 to $0.60 per passenger tyre (although anecdotal evidence suggests that it may be as high as $2.00 in some cases). Shredding equipment, because of steel in the tyres, is subject to breakdowns and high maintenance costs. Energy costs are quite high and the process generates noise and dust. The physical nature of tyres also results in the need for considerable manual handling to feed tyres into the machine.

It is estimated that approximately 100,000 tonnes of tyres are shredded in Australia each year, with the majority of this being prior to landfilling.

There is no commercial competition for shredding since it is generally an intermediate step in processing rather than a final product.

8.3 Waste avoidance

In the case of tyres, avoidance means reducing the rate at which waste tyres are generated. The means by which this can be achieved are to either reduce the distance travelled or extend the life of the tyre by decreasing the rate of wear. These issues are discussed in the following sections.

8.3.1 Reducing the distance travelled

Other things being equal, the generation rate for waste tyres is determined by the distance travelled. There is considerable pressure to reduce the level of road traffic for reasons not primarily associated with the generation of waste tyres, such as the costs of infrastructure to provide capacity to meet peak demand and environmental impacts including the greenhouse effect.

To a minor extent, changes to the type of vehicles can reduce the volume of waste associated with tyres or even the number of tyres39.

8.3.2 Reducing the rate of wear

The design wear life of a good quality passenger tyre is currently in the order of 50,000 to 65,000 km while the wear life of a truck tyre is considerably longer, in the order of 150,000 km for a drive wheel and linger for a trailer wheel. The expected life of tyres has increased considerably over recent decades with the introduction of radial belted tyres and improvements in tyre manufacturing technology.

The life of road tyres should be considered in two separate parts:

The tread. When this reaches the wear limit - 1.6mm for a passenger tyre - the tyre reaches the end of its ‘first’ life.

The casing. A good casing can remain serviceable for a number of new treads. A good car tyre casing has a life of between 100,000 to 200,000 km while a good truck casing has a life of 650,000 to 750,000 km. Generally, a car tyre can only be retreaded once, but truck tyres are routinely retreaded up to five times.

Different tyres have different wear rates and tyres can be designed and manufactured so as to maximise life. However, the longer life may be at the expense of tyre performance in other areas such as ride/comfort, wet handling, dry handling, aquaplaning, noise and rolling resistance. For truck tyres, characteristics such as ride comfort may be deemed to be of lesser importance and are sacrificed in the interests of extended tyre life to a greater extent than is the case for passenger tyres.

Several sources have claimed that tyre life will continue to increase due to advances in tyre technology and also to improved road conditions. A counter to these claims is the introduction to the tyre market of so called ‘cheap’ imports that have a lower life expectancy. Overall, recent increases in the life expectancy of tyres do not appear to have matched earlier gains, and predictions that tyres will last for the life of the vehicle remain remote.

The expected or design life of a tyre does not appear to be a factor in marketing of tyres in Australia. It is argued that availability of information on tyre life and other factors such as rolling resistance would help inform purchasing decisions that would favour longer life tyres over ‘cheap’ alternatives and perhaps promote the development and introduction of longer life tyres. The US has a tyre rating scheme in place to these ends, which is discussed above in Section 4.1.1.

Differences in expected tyre life across individual tyre models are in many cases dwarfed by the in-use variation due to factors such as driving behaviour (particularly speed and the severity of acceleration, braking and cornering), loads carried and abuse/damage, tyre maintenance, and the road conditions.

The effect of tyre maintenance or, as appears to be more often the case, lack of maintenance provides perhaps the best opportunity for reducing the quantity of waste tyres generated. Tyre maintenance includes maintaining appropriate pressure, tyre rotation and maintaining correct wheel alignment. Tyre pressure in particular is an area that could be significantly improved. The effect of incorrect tyre pressure (typically low pressure) is shown in Figure 8.1.

effect of low pressure on tyre life

Figure 8.1 Effect of low pressure on tyre life40

By applying the relationship in Figure 8.1 to the entire passenger vehicle fleet using the NRMA survey of tyres in Part II Table 3.1, the generation rate for waste tyres is estimated to be approximately 6% higher than if correct tyre pressures were maintained.

Despite clear instructions in owner's manuals, tyre pressure guide stickers in the driver's door jamb, and offers of free servicing and maintenance plans by tyre retailers, tyre maintenance appears to remain a low priority for many vehicle owners. A number of factors, such as the increase in self-serve petrol stations with limited access to tyre pressure hoses and the exceptional durability of tyres that seem to be able to absorb almost any amount of neglect and abuse, all contribute to poor maintenance.

The benefits of improved tyre maintenance are not restricted to extended tyre life but also include reduced fuel consumption and improved safety. These factors are potentially more beneficial to the environment and economy than longer tyre life and reductions in waste tyre generation and are worthwhile regardless of the waste tyre issue.

Increased public awareness of the issue and of the benefits of improved tyre maintenance is obviously an important approach to ‘avoiding’ the waste tyre management problem. Access to resources, such as accurate tyre pressure gauges and pumps and use of tyre valves that can indicate when the tyre pressure is low, are some of the other potential options. Finally, incorporating tyre maintenance and rotation in the periodic mechanical servicing of cars would also improve the tyre life.

 


38See for example EPAQ (1999), A Strategy for Managing Waste Tyres in Queensland.

39For example small car tyres weigh less than a large car tyre and a B-double truck has 34 tyres and carries nearly twice the weight/volume of a standard semi-trailer which has 18 to 22 tyres.

40Based on OECD (1980)