As an ongoing challenge for tyre manufacturers, recycling used tyre materials into usable tyre materials has continued to be increasingly complicated due to the ever-evolving and more complex sets of tyre material compositions. Manufacturers of tyres must establish a valid end-of-life cycle for tyres by utilising high-quality raw materials recovered from tyres returned after manufacturing. These high-quality raw materials will replace the current means of burning waste tyres for energy and burying them in landfills.

The worthy recognition of the "Hankook +1" programme is encouraging. Still, we must first understand why the performance of modern tyres depends upon the use of carbon black and why carbon black is so difficult to replace.

Carbon Black on Modern Tyres

The primary reason most experts consider carbon black the main component of modern tyres is that it serves many purposes in the construction. Carbon black provides rigidity and strength to the rubber and increases the tyre's ability to resist abrasive wear, or "wear", and increases the traction (grip) of tyres on vehicles while being driven. Carbon black also assists in dissipating heat created by the friction of driving on road surfaces. All of these attributes affect the lifetime and the safety of a tyre; any alternative that is developed to replace carbon black must be of equal quality to carbon black.

Due to their composition, recycled materials in tyres are typically easier to replace than carbon black, which presents challenges to the tyre industry. As an example, minor changes to the carbon black structure will alter the way rubber functions.

To address the latter concern, Best Hankook Tyres in Telford has adopted a pyrolysis-based approach, which produces a more uniform product.

Turning Old Tyres into Usable Building Blocks

This method uses low-oxygen conditions to extract useful building blocks from scrap tyres. The heat generated by pyrolysis will break the scrap down into gaseous, solid, and liquid materials, depending on the temperature and duration of the pyrolysis process. If processed and treated to the required purity levels, pyrolysis oil can be used to synthesise carbon black and carbon black-like materials for tyre manufacturing.

The key to producing tyre-grade carbon black through the pyrolysis process is to provide high-quality feedstock in a stable, reliable manner, with sufficient evidence of quality and consistency from the time the feedstock enters the tyre industry loop until it becomes a new tyre product.

This is where certification and supply-chain controls become central, not cosmetic.

What does the ISCC PLUS Certification contribute to Hankook Tyres?

ISCC PLUS Certification supports Hankook’s strategy for mass production of tyres by confirming the use of sustainable sources for the materials used to make the tyres, with a document trail for tracking sustainable source materials from “Farm to Market”. In addition, buyers and regulators are seeking proof, not promises, that tyre manufacturers are producing tyres from sustainable sources.

Now that the "what" has been determined, the next question is "How did they go about it?" Collaboration and process design are the key components to developing a sustainable supply chain.

The Tyre-to-Tyre Consortium

When a link in a material flow breaks, the entire system fails to function circularly. Waste tyre collection can function well. However, sorting the tyres Telford does not work well. Also, while pyrolysis may produce oil as a product and an intermediate, there may be issues with refining that oil. Carbon black has been proven to be a useful product; however, tyre manufacturers are often reluctant to use it due to its inconsistent performance. To address these challenges and build a functional circular-materials model, Hankook has implemented a consortium model that enables the development of a product chain from collection and sorting through to the manufacturing of finished tyres made from sustainable materials.

It matters because "tyre-to-tyre" doesn't just describe a single technology; it defines an overarching industrial workflow that encompasses all aspects of the tyre manufacturing process.

Why “Mass Production” is the Real Breakthrough?

The "mass production" aspect is a real breakthrough; most sustainability claims only extend to laboratory-scale or limited-edition products, while mass production brings all areas of the system into line. The procurement side must be able to produce high volumes; factories must be able to produce uninterrupted, with constant performance. On October 1, 2024, Hankook announced it will shift from technology development to repeatable production using CCB (certified carbon black), derived from end-of-life tyre pyrolysis oil.

This is important to everyday consumers, as the work done in this phase will increase the likelihood of consumers seeing sustainable materials in their normal product lines, not just in concept tyres.

Performance, Safety, and Trust

A balanced combination of performance, safety, and trust must remain a top priority in the tyre industry.

Tyres can only be manufactured from circular materials if they deliver the required levels of grip, braking, wear life, and handling predictability. Hankook's overarching sustainability messaging states that sustainable raw materials must support tyre performance and effectiveness. For the past several years, the company has worked with a variety of certified sustainable raw materials sourced from different suppliers.