End-of-Life Tyre Options: Baling, Shredding, Pyrolysis, and Retreading

By:     Conor Murphy

Choosing the Right End-of-Life Route for Used Tyres

When a tyre reaches the end of its useful life on a vehicle, the processing decision that follows is not simply about disposal. It is a choice between several routes with meaningfully different economic, environmental, and technical implications. The right choice depends on the tyre’s type and condition, the infrastructure available at the processing location, the markets available for the processed output, and the regulatory framework governing the specific route.

The four principal end-of-life routes for UK tyres, retreading, PAS 108 baling for civil engineering, shredding for crumb rubber and energy recovery, and pyrolysis, serve different tyre types and produce different outputs. A tyre that is a good candidate for retreading is not well served by shredding; a tyre that has failed structurally is not a retreading candidate and should go to a different route. Applying the right route to each tyre type is the basis of an effective end-of-life tyre management strategy.

Gradeall International specialises in the equipment for one of these routes, PAS 108 civil engineering baling, and supplies the upstream processing equipment (sidewall cutters, rim separators) that prepares tyres for other routes as well. With nearly 40 years of manufacturing experience and equipment in over 100 countries, Gradeall’s team has a detailed understanding of the tyre processing landscape and can advise on the equipment that supports each route. The tyre recycling equipment range is referenced throughout this guide.

Option One: Retreading

Retreading is the highest-value end-of-life route for tyres with sound casings. Rather than treating the whole tyre as waste, retreading salvages the casing (the structural core of the tyre that represents the majority of the material value and environmental impact) and applies new tread rubber over it, producing a functional tyre at significantly lower cost and environmental impact than manufacturing a new tyre.

Which tyres are retreading candidates. Truck and bus tyres are the primary retreading target. The casing of a well-maintained truck tyre, if not damaged by impact, overloading, or excessive heat, can be retreaded multiple times. Fleet operators with structured tyre management programmes assess each removed truck tyre for retreading viability and route sound casings to approved retreaders.

Car tyre retreading is technically possible but less commercially common in the UK than truck tyre retreading. Consumer demand for retreaded car tyres is limited by perception and by the relatively lower cost of new budget car tyres compared to the price differential between retreaded and new truck tyres.

The retreading process. The tyre casing is inspected non-destructively (buffed and X-rayed or shearography tested) to identify internal damage. Sound casings are buffed to remove remaining tread, cleaned, and then have new rubber applied either by hot retreading (new tread moulded and cured in a press) or cold retreading (pre-cured tread bonded to the buffed casing and cured in an autoclave).

Regulatory framework. Retreaded tyres for use on UK roads must comply with ECE Regulation 108 (for car tyres) or ECE Regulation 109 (for truck tyres). Retreaders approved under these regulations produce tyres that meet the same performance and safety standards as new tyres for their specified application.

Environmental advantage. Retreading uses approximately 70 percent less oil and produces approximately 70 percent fewer CO2 emissions than manufacturing a new tyre. For fleet operators with sustainability reporting obligations, a documented retreading programme for truck tyres is a measurable contribution to Scope 3 emissions reduction.

Option Two: PAS 108 Civil Engineering Baling

For whole passenger car and light van tyres that are not retreading candidates, PAS 108 civil engineering baling is typically the highest-value recycling route available. Rather than shredding the tyre into crumb rubber, baling uses the tyre in its whole form as a structural engineering material.

What PAS 108 requires. PAS 108, BSI Publicly Available Specification 108, defines the requirements for tyre bales used in civil engineering. The specification covers bale dimensions (typically 1.55 to 1.6 metres long, 1.2 metres wide, 0.7 to 0.8 metres high), minimum bale mass (approximately 1,000 to 1,100 kg per bale), tyre composition (no rims, no loose material), and the geotextile wrapping requirement. Bales that meet these specifications are accepted by civil engineering contractors for use in approved applications.

Civil engineering applications. PAS 108 bales have well-established uses across several civil engineering applications:

Road construction: tyre bales as lightweight fill behind retaining walls and beneath embankments, reducing vertical stress on weak subgrades. Coastal and river bank protection: bale structures that absorb hydraulic energy while remaining structurally stable. Sustainable urban drainage (SUDS): tyre bale cores in drainage systems that allow water infiltration through the geotextile wrapping while the rubber provides structural support. Retaining walls: bale stacks that provide gravity-based retaining structure with lower cost than masonry or concrete alternatives. Slope stabilisation and repair of failed slopes using tyre bale structures to provide both drainage and structural support.

Gradeall’s MKII tyre baler produces PAS 108 bales at up to six per hour, with each bale containing approximately 100 passenger car tyres. The MK3 tyre baler and truck tyre baler extend baling capability to different tyre formats. Inclined conveyor systems including the inclined tyre baler conveyor automate tyre feeding for consistent high-throughput baling.

Commercial position. Tyre bales sold to civil engineering contractors command prices that make the baling route commercially attractive for tyre processors at appropriate volumes. The price per bale varies with project demand and regional market conditions; a tyre processing business with good connections to civil engineering projects in its region can develop reliable revenue from PAS 108 bale sales.

Option Three: Shredding for Crumb Rubber and Energy Recovery

For tyres that are not suitable for retreading or whole baling (including truck tyres with worn or damaged casings, OTR tyres, heavily damaged car tyres, and mixed-type streams where whole baling is not viable), shredding and granulation to crumb rubber is the standard processing route.

The processing sequence. As described in Gradeall’s guide to rubber recycling, the shredding route involves primary shredding, steel separation, secondary granulation, fibre separation, and screening to produce crumb rubber at the required particle size. Front-end processing with sidewall cutters and rim separators improves shredding efficiency and material recovery.

Gradeall’s sidewall cutting range, including the truck tyre sidewall cutter and OTR tyre sidewall cutter, prepares truck and OTR tyres for shredding by reducing their size and releasing some of the structural tension in the tyre before it enters the primary shredder. The tyre rim separator and truck tyre rim separator recover steel and alloy wheels from tyres before they enter the shredding line.

Crumb rubber end markets. The primary crumb rubber end markets are sports surfaces (artificial turf infill, playground safety surfaces, athletics tracks), rubber-modified asphalt for road construction, and various industrial rubber products. The artificial turf market is subject to ongoing regulatory debate in Europe; UK regulatory positions on synthetic turf rubber infill are evolving. Road surfacing with rubber-modified asphalt is a growing and relatively stable end market supported by government road maintenance programmes.

Energy recovery. Tyres that are too degraded for material recycling (contaminated, mixed, or otherwise unsuitable for crumb rubber production) may go to energy recovery, primarily in cement kilns where the rubber’s high calorific value substitutes for coal and the ash is absorbed into the cement clinker. Energy recovery is lower in the waste hierarchy than material recycling; it is appropriate for tyres that cannot be processed by higher-value routes rather than as a first choice.

Option Four: Pyrolysis

Pyrolysis converts tyre rubber into pyrolysis oil, recovered carbon black (rCB), steel, and non-condensable gas through thermal decomposition in the absence of oxygen. As covered in Gradeall’s rubber recycling guide, pyrolysis is a developing technology that has matured significantly in recent years.

When pyrolysis makes sense. Pyrolysis is most applicable to tyre fractions that are difficult to recycle through other routes: finely shredded rubber that is below the size threshold for crumb rubber applications, mixed rubber containing significant textile fibre that impairs crumb rubber quality, and very contaminated rubber that would produce low-grade crumb.

The commercial position. Pyrolysis oil from tyre processing can be sold as fuel or as a chemical feedstock. Recovered carbon black has potential as a substitute for virgin carbon black in rubber and plastic applications. The commercial viability of a pyrolysis facility depends on the consistency and quality of the rCB product and the price differential between rCB and virgin carbon black, which is volatile.

Regulatory requirements. Pyrolysis facilities require environmental permits covering the thermal process, emissions to air, and management of the solid and liquid outputs. The permit requirements are more demanding than for mechanical processing facilities; regulatory engagement should begin at the early planning stage.

Comparing the Routes: A Decision Framework

The highest-value routes, retreading for truck tyres and PAS 108 baling for car tyres, should be applied to every tyre that meets the technical criteria before lower routes are considered. This hierarchy maximises both the economic return from tyre processing and the environmental benefit by retaining more material value in use.

“The hierarchy matters,” says Conor Murphy, Director of Gradeall International. “A truck tyre that should be retreaded but gets shredded instead represents lost value and lost environmental benefit. A car tyre that should be baled to PAS 108 but goes to a shredder instead is the same problem. Our equipment is used to produce the highest-value outputs from each tyre type, and that’s the principle we bring to every equipment conversation with tyre processors.”

Contact Gradeall International for tyre processing equipment across the full tyre recycling range, supporting the front-end processing that enables each tyre to reach its highest-value end-of-life route.

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