In the 1930s, when rubber became one of the essential commodities, selection was never a problem because we had only Natural Rubber (NR) that time. Today, beyond 2010, there are number of elastomers are being used in the industry and the choice is typically important with respect to the competitive advantage of both, durability in the service and cost.

 

NR was called rubber because it could have rubbed out pencil mark. When other synthetic rubbers were produced, they had also similar property of rubbing out pencil mark, but were called elastomers because NR was then typically identified as Rubber. However, both NR and other synthetic rubber (SR) together are called elastomers, because they had typical elastic properties and interestingly, all rubber and elastomers are high polymers. From the time 1930 , industries have increased many folds of time. Engineering requirement in the manufacturing industries, with respect to temperature, pressure and durability have also simultaneously increased and our demand on the applications have also been increased.

CAPTION Fig.1: Asia Pacific Total Elastomers (54%), NR+SR

 

With very competitive demand in the market, all rubber properties cannot be achieved only by NR. Balancing critical demand for rubber applications, that we require in our day to day life, use of SR or blending with SR has become very common practice in the industry today.

 

For example, other than pneumatic tyre, there is hardly any uses of NR these days in automotive industries. Uses of various grades of EPDM, Silicone rubber (Q), Nitrile rubber(NBR), Fluoro Elastomers (FKM) , Perfluoro Elastomers (FFKM) , Hydrogeneted Nitrile rubber (HNBR), Chlorosulphonated Polyethylen (CSM), Polychloroprene(CR) , Polyurethane Rubber (AU/EU), Fluorosilicone Silicone Rubber (FQ) etc. have been increased due to typical automotive parts requirement. Since automobile spares are now mostly manufactured in Asia Pacific countries, they are the largest consumer of total elastomers (Fig.1).

 

CAPTION Fig.2: Only SBR is the highest (47%) synthetic rubber

 

After NR, the next high consuming elastomer is SBR (Fig.2) because of its higher filler and oil loading capability and higher abrasion resistant quality. After SBR, the next high quantity rubber used is BR, followed by IIR (BIIR,CIIR) and EPDM. Recently silicone rubber uses have increased many fold times in Western countries, China, Japan, Korea and in India. However, the total SR uses remains highest in Asia Pacific(Fig.3).

 

CAPTION Fig.3: Asia Pacific Highest Consumer of SR (48%)

 

In critical applications, it is therefore, advisable to give considerable thought, or take advice, on the formulation of the compound. As the potential for 'tailoring' compound to specific applications is essentially limitless, it is often advisable to carry out preliminary qualification tests to ensure that the compound chosen will perform as intended by customer need.

A considerable thought in critical applications, for the formulation of the specific compound need considerable experience with selecting raw materials and art of processing. Very common mistakes by rubber compounder is mostly related to incorrect selection of (1) ingredients, (2) their doses, (3) rubber blends and (4) correct machines. Rubber compounding is an art of developing rubber mixtures with suitable raw material and their doses, that will perform in desired services but with minimum cost possible such that product can be competitive in the market and can be processed well in machines without any difficulties faced by man and machines.

 

There are broadly two classes of Rubbers or elastomers, they are Natural Rubber (NR) and Synthetic Rubber (SR). NR occurs naturally in the plant and hence the name but all synthetic rubbers are man made rubbers and are produced by chemical synthesis. Among the Synthetic elastomers, there is again two category; one is general purpose rubbers (GPR),which can be used as equivalent to NR, e.g., Butadiene Rubber (PBR) and Styrene Butadiene Rubber (SBR) and the other category is specialty elastomers. Specialty elastomers are generally costlier than GPR and are only used in special purpose. Following are the list of specialty elastomers ,which are widely being used in rubber industry beyond 2000:

 

Butyl Rubber (IIR), Chlorobutyl Rubber (CIIR), Bromobutyl Rubber (BIIR), Chlorinated Polyethylene(CM), Chlorosulphonated Polyethylen (CSM), Ethylene Acrylic(EEA) , Ethylene Propylene Rubber(EPM) , Ethylene Propylene Diene Rubber(EPDM), Fluoro elastomers (FKM), Hydrogenated Nitrile Rubber (HNBR), Isoprene Rubber (IR), Nitrile Rubber(NBR) ,  Polyacrylic Rubber (ACM), Perfluoro Elastomers (FFKM), Polychloroprene (CR) , Polysulphide Rubber (TR) , Polyolefin Elastomer (POE),   Polyurethane Rubber (AU/EU) , Silicone Rubber(Q), Fluorosilicone   Silicone Rubber (FQ) etc.

 

Elastomers having carbon-carbon double bond on the elastomeric backbone could be cross-linked with sulphur and accelerators. Many of these elastomers are also could be cured with organic peroxides, examples are NR,SBR,BR, AU/EU, CM, CR,CSM,EPM,EPDM,FPM,NBR,HNBR,IR,POE,Q,FQ. Elastomers that cannot be cured with organic peroxides are; ACM,IIR,CIIR,BIIR,ECO.

 

Rubber compounding

 

Rubber compounding is an art of developing rubber mixtures with suitable raw material and their doses, that will perform in desired services but with minimum cost possible such that product can be competitive in the market and can be processed well in machines without any difficulties faced by man and machines. In all rubber industry today, the biggest challenge is cost reduction of a good quality product. During selecting raw materials, therefore, the cost of these will also play a vital role in compound designing.

 

A rubber product might require desired physical properties and ageing properties. For this one need to add particular reinforcing filler or a suitable combination of reinforcing fillers to have desired physical properties. The typical ageing resistant property may be achieved with only NR by adding suitable anti-degradants or, NR could also be blended with synthetic elastomers with better ageing resistant property. NR being cheaper and easily available it is the first choice having good strength, abrasion , tear strength and low heat development in dynamic condition. A synthetic rubber product might require good green strength , in that case either NR or blend of rubber is the choice. For example, for better green strength of CIIR, it is often blended with NR.

 

CAPTION Fig.4: Turn-up Bladders

 

A rubber product may require a specific need , say air retention property or oil resistance property. For the former case the choice is essentially butyl rubber (or, halobutyl rubber , CIIR,BIIR) and for the later it is usually, NBR/HNBR and for both oil resistance and air impermeability, the usual choice is NBR / HNBR rubber (Turn-up bladder for tyre building operation, Fig.4). For a typical product, if the property demands oil resistance at 200 ⁰C, then the choice is FKM (Fluoroelastomers) or Q. For resistance upto 328 ⁰C , it is FFKM.

CAPTION Fig.5: Typical Industrial Gaskets

 

Heat resistance property is typically related to product durability and sustainability at desired temperature and is very important for various industrial gaskets (Fig.5). For temperature resistant rubber compounding and following temperature resistance of the polymer is important, NR ~ 65 °C, SBR ~ 75 °C, NBR ~ 110 °C, HNBR ~ 180 °C, Q ~ 200 °C+, FKM ~ 240 °C, FFKM ~ 328 °C. The temperature ranges quoted are only a rough guide, because the temperature resistant property also depend on the typical compound design as well, depends upon the particular application, and may depend on detailed differences between alternative versions of the same rubber.

 

Rubber compound is always developed as per customer need. For any rubber article, the first choice is the selection of right rubber. Rubber is selected mostly on the basis of :

 

• Cost
• Heat and/or Oil Resistance
• Temperature Requirements
• Energy Absorption
• Seal Ability
• Flex Resistance
• Water Resistance
• Gas Impermeability
• Electrical Properties
• Abrasion Resistances
• Dynamic Properties
• Flame Resistance

 

Rubber compound related definitions

 

• Elastomer, a polymeric material that recovers substantially to its original shape after significant deformation at room temperature.
• Compound, a mixture of elastomer and other materials that is intended to process (mold) satisfactorily and meet end-use specifications.
• Filler, a particulate material added to an elastomer that modifies both the workability and the end-use behavior of the resulting composition.
• Plasticizer, a material added to an elastomer to improve its workability.
• Resins are added to improve rubber tack.
• Waxes also used as plasticizer , are also added for smooth finish of rubber articles.
• Antioxidant, a chemical added to a compound to slow or prevent oxygen attack on the compound.
• Antiozonant, a chemical added to a compound to prevent ozone attack.
• Cross linking agent, a chemical added to a compound to link the long molecules in a polymer together, or to assist in the cross-linking process.
• Accelerator, a chemical added to a compound to increase the rate of cross-linking in the compound.
• For example, sulfur links the long molecules, while an accelerator increases the cross-linking rate.
• Retarder, a material added to an elastomer compound to delay the onset of cross linking (scorch).
• Vulcanization is same as cross-linking but with sulphur.
• Peroxide also helps in cross-linking process.

 

 

Elastomer blends

 

Elastomer blends often creates problem when two different types of unsaturated rubbers are mixed and vulcanized together. For example, NR and IIR have two different unsaturation level and hence both sulphur , ZnO and black flows more towards polar rubber, on NR phase, and results undercure in IIR phase and the resultant blend vulcanizate becomes spongy and cannot be used.

 

GPR (NR,SBR,BR) rubber could be blended to any proportion. For higher synthetic rubber level (BR,SBR) , accelerators dose is often adjusted to higher side and sulpur level is adjusted to lower side, because for equivalent curing, BR, SBR requires more accelerators as compared to NR. Stearic acid is added 2-3 phr with only synthetic elastomer and for NR, stearic acid dose of 0.5 phr is enough.

 

CAPTION Fig.6 : Micro Dispersion of Rubber Blends

 

Practically most of the polymers are not miscible to 100%, polymer blends usually consist of micro-dispersion of one rubber into the other rubber and this results after intensive mixing of these two different polymers. These micro dispersed rubber often has dimensions around 0.1-1.5 nm(Fig.6). When fillers are also mixed into such blends, a situation may develop in which the filler unevenly distributed between two phases. Such uneven distribution of fillers, naturally effects the uniformity of compound physical properties. In most blends the effect on the properties of blended elastomers depend on:

 

1. The polymer compatibility
2.  Distribution of fillers in different phases and
3. The degree of cross-links between rubber phases

 

Though NR,SBR,BR could be blended to any proportion , yet the blended phases are not compatible to hundred percent and there is also phase separation, where, on proper identification one can witness that there is phase separation with NR & SBR, NR & BR, BR & SBR. However, upon proper mixing these phase differences could be minimized (Fig.7) such that the resultant blend gets cured almost homogeneously . That is why very highly dispersed NR (5 to 10 parts) could also be co-cured with IIR.

 

 

CAPTION Fig.7 : Well Dispersed Rubber Blends

 

 IIR cannot be blended with GPR but can be blended with EPDM (having ENB diene content between 2-3 mole%) to any proportion. Higher diene content EPDM rubber (ENB, >9.0% mole) could be well blended with GPR. If high diene content EPDM is blended with IIR, filler, sulphur, accelerator and zinc oxide flows more towards EPDM than IIR. IIR could be blended with CIIR and BIIR to any proportion. Such blend is often used in making tyre inner-tubes and hose jacket compounds. When CIIR and BIIR doses are on the higher side with IIR (>60phr) it is worthwhile that zinc oxide is added in the final batch since zinc oxide is curative for CIIR & BIIR.

 

Besides zinc oxides, CIIR and BIIR can also be cured with sulphur/accelerator system as well. However, for very good heat resistant property, they are often cured with ZnO. Highly dispersed plastic (LDPE) could also be blended with CIIR/BIIR with no detrimental effect but with improvement on air permeability.

 

CIIR and BIIR could be blended to any proportion with GPR. Such blend is often used in tyre inner liner. When CIIR and BIIR doses are on the higher side (>60phr) both zinc oxide and amine type anioxidant/antioxonates are added in final batches as these are curatives in CIIR and BIIR.CIIR blend with GPR and EPDM is used in PC sidewall for glossy finish sidewall and addition of CIIR also help to reduce the curing time of PC tyre. Blend of EPDM/NR/SBR and EPDM/NR/SBR/CIIR are often used in tyre side wall compound for better look.

 

CR rubber is not normally blended in the industry as it is mostly used in adhesive industry. However, they can be blended to any proportion with GPR. In adhesive industry crystallinity is important and CR gives the highest degree of crystallinity among all general-purpose rubber. CR could be blended with IIR , close to 5-15 phr, for bladder making and in general, only 5.0 phr is added in the beginning of the mixing cycle.

 

In bladder mixing, Zinc oxide could be mixed with CR in master batch. CR is premasticated in mixing mill for making bladder compound, before adding in Banbury.CR/BR blend is used in hose covers.CR could also be blended with GPR at any proportion like CIIR. Both zinc oxide and amine type antioxidant / antioxonates are added in final batches as these are curatives in CR and CIIR.

 

In general Silicone rubber (MQ,PMQ,VMQ) cannot be blended with any other rubber because of phase difference problem but highly dispersed EPDM could be blended with it upto 10 -15 phr. EPDM/Q blend is used in heat resistant cover roll compound.

 

EPDM, being a good elastomer as weather resistant and heat resistant is often blended with number of other elastomers to get the benefit of the vulcanisates.

EPDM/CR blend are very popular in making gaskets. EPDM/IR blend is widely used in car wiper rubber blades. EPDM/SBR blends are used in gaskets, sponges and hose stocks. EPDM/CSM blend is used in transmission belt, conveyor belt and in hose covers. EPDM/LDPE blend is very popular in making cable insulation compound.

 

NBR in general, is not blended with other elastomers as this rubber having higher degree of polarity , is exclusively used for oil resistance property. It may have acrylonitrile content ( ACN) ranging from 18-50%. Incase of higher oil resistance, the elastomeric grade is selected with higher ACN. For better abrasion however, 10-20 phr of BR could be added to NBR with the aid of good dispersing agents , used in shoe sole, high abrasion resistance rolls and in conveyer belts. Higher ACN content will have better abrasion property. NBR could be cured both by sulphur/accelerators or by peroxides. Hydrgenated NBR (HNBR) has emerged into market with better heat resistant property as compared to NBR. For intermediate heat resistant property NBR and HNBR could be blended.

 

NBR/SBR blends used in hydraulic hose tubes, high pressure hose, belt cover, idler roll compounds and in gasket compounds. NBR/PVC blend and NBR/PVC/BR blend are used for roll cover compound, very popular in electric cable insulation and in closed cell sponge applications in shoe industry. XNBR/PVC blend is used for heavy duty cable jackets, roller cover, belt cover, hose cover stocks etc. NBR/IR blend and NBR/TR blend is popular in colored or non-black roll covers. The later is mostly used in printing roll cover compound.

Sustainability has become critical for the tyre industry due to its heavy reliance on fossil-based raw materials, significant carbon footprint across the product lifecycle and the massive volume of end-of-life tyres generated annually. Shifting towards renewable, bio-based and recycled materials helps reduce greenhouse gas emissions, conserve resources, minimise microplastic pollution from tyre wear and address regulatory and consumer demands for greener mobility solutions. Without accelerated innovation, the industry risks falling short of global climate targets while facing supply chain vulnerabilities and reputational challenges.

The global tyre market is valued at around USD 290 billion in 2025 and is estimated to reach USD 299 billion in 2026 as per MarkNtel. It is projected to attain USD 387 billion by 2032, registering a CAGR of 4.39 percent during 2026–2032. Interestingly, the Passenger Car segment leads the global tyre market with approximately 42 percent of total demand. Radial tyres dominate the global tyre market with around 88 percent share. Furthermore, Asia-Pacific holds the largest regional share at approximately 37 percent.

In an exclusive interaction with Tyre Trends, C Harimohan, Head of Corporate R&D (Materials and Compounding) at Yokohama Off-Highway Tires (YOHT), shares his views on the tyre industry’s push towards true sustainability. He highlights the technical, economic and regulatory hurdles that lie ahead as the sector targets ambitious 2050 goals.

THE SUSTAINABILITY IMPERATIVE

It is no secret that the tyre industry is undergoing a profound shift, be it managing raw material supply chain, sustainability targets and geopolitical challenges, among others.

“See, I think we are undergoing a very special kind of scenario now,” Harimohan observes. While the core manufacturing process and raw material mixes have remained relatively stable, sustainability has moved from a ‘fashion word’ of a decade ago to a serious business priority.

“In the last two to three years, or let us say three to five years, we have started taking it more seriously because almost all the companies have declared that by 2050, 100 percent of the raw materials would be either renewable or recycled,” he says.

This target, however, comes with limited current visibility on delivery. Today, roughly 65 to 70 percent of tyre raw materials are derived from fossil sources, primarily crude oil.

“Around 30 percent only comes from the natural rubber; the remaining major part becomes a synthetic rubber, carbon black and almost all the chemicals which are derived from crude,” he explains. The central challenge is transforming these fossil-dependent components into renewable or recycled alternatives.

Recycling, though not new, presents its own limitations. “When you devulcanise the rubber, the kind of strength it has got originally, it is dropping drastically,” Harimohan notes.

“So it is not a 100 percent one-to-one substitution of the original compound or raw materials what you have. So you cannot go beyond a level,” he shares. This creates an inherent performance compromise that undermines the very idea of sustainability if safety and durability suffer.

BALANCING PERFORMANCE, QUALITY AND PRICE

The trade-off between sustainability, performance and cost emerges as one of the industry’s most pressing dilemmas. Harimohan poses the critical question, “What about trade-off between performance, quality as well as price? Because you could have the best recycled tyre, but if it does not perform as per consumer expectations or as per what is expected from its non-sustainable tyre or what people are used to, what are the challenges that have taken place?”

Even a near-100 percent sustainable tyre remains commercially unviable at present. “I can conceptually make a close to 100 percent, if not 100 percent, you can say a sustainable tyre which is produced from only renewable or recycled materials. But then it has to be at least three to four times the cost or the price would be three to four times what it is today. But then there has to be somebody who will pay for it,” he says.

Harimohan further explains that without external pressure, market adoption will be slow. “Unless and until it is enforced by a regulatory or by government, I do not think it is going to happen.”

He believes, “Even if we can market it as sustainable tyre, unless and until there is somebody who can pay for it, I think it is not going to happen.” Nevertheless, he remains optimistic about ongoing innovation.

“Most of us, almost all the R&Ds across the world are working towards it, how to make it more and more towards that 100 percent level, but at the same time without having a damage to the performance and almost at the same price you should be able to sell it,” says the executive. He anticipates meaningful progress over the next decade or two.

SUPPLY CHAIN PRESSURES AND THE ROAD AHEAD

Geopolitical tensions have added further complexity to an already intricate global supply chain. A single tyre incorporates ‘at least 60 to 70 different raw materials’ sourced from around the world. “All the geopolitical situations are affecting significantly on all the procurement, the supply chains are getting affected and it is affecting the whole production, supply of the tyre,” Harimohan confirms. “Tyre is no different. It is getting affected.”

On the question of segment-wise adoption, he sees OEM-driven momentum leading the way. “This is happening in almost across the segments, but I feel this is a bit more driven by the OEMs. So I think it may be the PCR segment which should be moving a little far ahead of others or even the two-wheeler would be going a little ahead of other segments,” he says, noting slower progress expected in off-highway and OTR applications.

Responding to a query on new trends in the industry, Harimohan acknowledges there lies huge potential for disruptive technologies. “I feel something will come to gradually replace the tyres. Like airless tyre could be one of the examples, there can be flat tracks coming,” he remarks.

Despite the industry’s traditional inertia, he believes change is inevitable, “Even though tyre is more of like a traditional and there is a lot of inertia to change, but I think going forward, there should be or there would be something which could potentially replace tyre all together. I mean, I think we should hope for that.”

The path to a fully sustainable tyre industry is neither simple nor short, but Harimohan’s insights reveal a sector actively confronting difficult trade-offs.

With continued R&D focus and potential regulatory support, the promise of high-performance, affordable and truly green tyres is still some decades away from becoming a reality.

The Association of Natural Rubber Producing Countries (ANRPC) has released its Monthly Natural Rubber Statistical Report for June 2026, documenting a period of price resilience within the sector. This stability persisted despite seasonal supply improvements and firm downstream demand, set against a backdrop of significant geopolitical friction and macroeconomic volatility. The month of July presented a starkly different energy landscape compared to June, as renewed regional conflicts and major shipping route disruptions replaced the brief period of stability following the provisional reopening of the Strait of Hormuz.

The escalation in Middle Eastern tensions exerted considerable upward pressure on global energy markets. Brent crude oil averaged approximately USD 83.76 per barrel in July, with the spot price surging to USD 96.95 per barrel by the end of the month. This sharp increase was primarily attributed to fears of potential restrictions on oil shipments through the strategic waterway, amplifying supply risks and embedding a higher risk premium within oil pricing structures.

Physical natural rubber prices exhibited divergent trends across major grades during the month. The Kuala Lumpur market saw SMR-20 average USD 2.22 per kilogramme, representing a month-on-month decline, while STR-20 in Bangkok followed a similar downward trajectory. RSS-3 also registered a decrease, contrasting with RSS-4, which posted a notable gain. Latex-in-bulk prices softened over the same period. Trade flows showed mixed results, as Chinese imports contracted, while significant import growth was recorded for India, Viet Nam and Malaysia. On the export front, shipments from Thailand, Viet Nam and Malaysia advanced, whereas Cambodia and Indonesia experienced moderate declines.

For the full year 2026, the ANRPC projects global production to expand by over two percent to reach 15.279 million tonnes, driven primarily by anticipated increases in Thailand, China, India and Malaysia. However, on a monthly comparative basis, July 2026 production is estimated to be over five percent lower than the same month in the previous year, though seasonal recovery is expected in key producer nations. Global demand is forecast to grow modestly by 0.4 percent for the year, with consumption in July rising year-on-year, supported by robust tyre manufacturing and electric vehicle-related demand, as well as a strong manufacturing performance and record auto sales in India.

Currency valuations saw the Malaysian ringgit and Thai baht trade within defined ranges against the US dollar. Futures markets reflected the mixed sentiment, with the SHFE September 2026 contract averaging 16,802.61 CNY per tonne, while the SGX September 2026 contract averaged USD 2.14 per kilogramme, both registering month-on-month declines. The overall data suggests a market navigating the complex interplay of supply recovery, shifting trade dynamics and persistent geopolitical uncertainty.

Flexsys, a prominent entity in material science and advanced tyre additives, has announced two significant advancements in its quest to develop a substitute for the chemical 6PPD. The company is progressing towards a new era in tyre manufacturing, having identified two primary molecular candidates that will undergo extensive evaluation. This development follows a prior announcement in November 2025, where Flexsys revealed it had created the first viable alternative to the established antidegradant.

The two finalist molecules have successfully passed rigorous internal and external testing, meeting stringent safety, performance and environmental standards. Significantly, neither compound belongs to the PPD chemical family, and crucially, they do not produce a quinone transformation product during usage. With the initial screening phase complete, Flexsys is now concentrating on expanded testing for these candidates, with the ultimate goal of selecting a definitive replacement for 6PPD in tyre production.

In a parallel effort to ensure environmental safety, Flexsys has formalised a Cooperative Research and Development Agreement with the U.S. Geological Survey. This collaboration is designed to independently and thoroughly assess the potential effects of the two molecules on aquatic ecosystems. Building upon a previous CRADA with the U.S. Department of Agriculture, this new agreement with the USGS represents a critical phase in determining the complete aquatic toxicity profile. The research will employ novel testing methodologies that extend beyond standard chemical registration requirements.

Under the agreement, scientists from the USGS Western Fisheries Research Center, alongside other USGS divisions, will study the molecules and their breakdown products. The focus will be on the impact on Pacific salmon and other aquatic species, utilising innovative cell-line research to pioneer new testing methods. This approach aims to create alternative assessment tools applicable to a wide range of chemicals. The CRADA formalises and expands upon preliminary testing that had already commenced at the research centre.

Flexsys acknowledged the support from the Economic Development Administration’s Tech Hubs Program, as a member of the Akron Sustainable Polymers Tech Hub. Concurrently, the company is optimising the process chemistry for both candidates to facilitate efficient, large-scale production. Both molecules utilise intermediate chemistry similar to that used for 6PPD, allowing the industry to leverage existing manufacturing assets. This strategic approach is expected to promote faster adoption and reduce overall investment costs while Flexsys continues its engagement with global regulatory agencies for commercial approval.

Carl Brech, Chief Executive Officer, Flexsys, said, “The tyre industry has been waiting for two things: a molecule that actually works and independent proof that it is safe. As of today, both are in hand or in motion. With tyre and environmental safety testing underway, the focus has shifted from finding a potential replacement to thorough validation, regulatory approval, scale-up and industry adoption.”

Neil Smith, Chief Technology and Sustainability Officer, said, “This marks a significant milestone for our team, and we’re pleased to announce we’ve narrowed our efforts to two final molecules that continue to meet our strict targets for in-rubber performance, scalability, toxicity profile and environmental sustainability. The selected alternative must be reliable and safe, not only today but for decades to come. USGS expertise provides independent evaluation with a level of rigour we could not execute on our own. We are proud to help pioneer novel toxicity-testing methods and eager to see the results.”

Michael Schmidt, Center Director, U.S. Geological Survey Western Fisheries Research Center, said, “USGS has spent the past five years studying the effects of 6PPD on aquatic species and developing innovative methods to screen the safety of potential alternatives. For nearly a century, the Western Fisheries Research Center has provided objective science to support management of aquatic species across the Western United States.”

Aircraft tyre retreading may resemble truck tyre retreading on the factory floor, but the similarities end there. Stringent US Federal Aviation Administration (FAA) oversight, exhaustive inspection protocols and extensive documentation make it one of the most tightly regulated segments of the tyre industry. According to President of Central Marketing Inc., these rigorous requirements coupled with high upfront investment and the dominance of major tyre manufacturers have created a niche market where only a limited number of players can compete.

Tire Retread Information Bureau mentions that over 100,000 retreaded tyres are done annually in United States, while another report published by the United States International Trade Commission on retreaded tyres in 2012 stated approximately 80 percent of aircraft tyres in US are retreaded and that retreading saves commercial and military operators over USD 100 million annually.

Since publication of the report over a decade ago, the state of the tyre retreading industry remains quite optimistic. Market Research Future estimated that US aircraft tyre retreading market will reach USD 1.42 billion by 2035, up from USD 948.2 million in 2025.

However, aircraft tyre retreading demands for stricter regulatory oversight than conventional truck and bus tyre retreading.

According to President Central Marketing Inc Edd Burleson, “FAA certification, rigorous inspections, extensive documentation and high entry barriers define the sector, where major tyre manufacturers dominate and independent retreaders serve mainly private aircraft operators.”

In a tete-a-tete with Tyre Trends, he delves into the dynamics of the aircraft retreading industry of United States and North America as his company has been a supplier of retreading machinery in these markets for over four decades.

“Although aircraft tyre retreading follows the hot retreading process, with many of the same steps seen in truck and bus radial retreading, the level of oversight is substantially higher. The process is fundamentally similar but is much more tightly controlled,” contended Burleson.

Everything is Federal Aviation Administration (FAA) certified. The inspection procedures are much stricter, there are more process controls, much more record-keeping and the Federal Aviation Administration oversees the entire process. The basic manufacturing process is similar, but the level of control and inspection is significantly higher.

He added that the dominance of major tyre manufacturers and strict regulatory requirements make it difficult for independent companies to enter the sector. And that’s because the smaller independent retreaders mainly service the private aircraft market rather than the major commercial airlines.

“Not everyone has the inspection capabilities or qualifications required to obtain an FAA license to retread aircraft tyres. It’s a speciality market and different from commercial truck tyre or OTR retreading,” he added.

Obtaining regulatory approval requires substantial investment before any licence is granted. A company will have to establish a plant, demonstrate its entire retreading process, undergo inspections and prove that it has the capability to perform aircraft tyre retreading.

“It’s not simply a matter of applying for a license and getting approval. You take on the risk of investing in the facility and processes before knowing whether you’ll actually be approved,” Burleson said.

In addition, entering the market isn’t easy because new plants will compete against major players like Goodyear, Michelin, Dunlop and Bridgestone. Hence, as an independent company, it’s generally conducive to enter the private aircraft market.

Burleson said the industry’s structure further limits competition because manufacturers sell tyre services rather than tyres themselves.

“The major players manufacture the new tyres and they’re not selling tyres but the service, most which is charged per cycle,” he said.

MARKET DYNAMICS

Aircraft tyre retreading remains a stable and highly specialised market. “The market across North America is well developed because airlines routinely retread their tyres as part of their operating model,” said Burleson.

The airlines themselves are responsible for maintaining the tyres including tyre pressure and general maintenance. The tyre company is responsible for supplying the tyres to the airlines and get paid on a per cycle basis. A cycle here means an entire take-off to landing cycle.

The number of times an aircraft tyre can be retreaded depends on the tyre size and aircraft type. “Some aircraft tyres can be retreaded two or three times, while others can be retreaded five or six times,” Burleson said.

Retreading significantly lowers operating costs for airlines by extending tyre life, he added. As a result, the cost per cycle comes down substantially. If airlines charged the same cost per cycle while using only new tyres, it would be three to four times more expensive.

The company supplies shearography inspection systems, repair machines, buffing machines, rubber extruders, laser engraving systems and curing presses. Its clientele includes Michelin, Bridgestone, Goodyear, Dunlop and one independent aircraft retreader, Wilkerson, in United States.

Besides, Central Marketing has been a servicing supplier to the tyre retreading industry as well as off-the-road, light truck, aircraft and the new tyre industries for 49 years. Its top-of-the-line computerised products have varying degrees of automation. Its base of operations is in Colonial Heights with a staff of 24 people.

Burleson described aircraft retreading as a stable market with limited growth because of the relatively small number of retreaders.

“The market is limited by the number of retreaders so it’s more of a stable market. Growth is typically around 3–5 percent annually. There’s no major boom like you’d see in an emerging market,” he said.

Unlike commercial truck tyre retreading, the aircraft sector in North America has not been affected by imports from Asian manufacturers.

“Bridgestone has one plant in US, Michelin has one, Goodyear has two and the total number of aircraft retreading plants isn’t very large,” Burleson said.

Outside United States, the market is even smaller.

“There’s a small aircraft retreader in Mexico and there isn’t any aircraft tyre retreading in Canada,” he said.

MAKING THE RETREADS

Aircraft retreading equipment differs from machinery used in commercial tyre retreading because aircraft tyres require greater precision during processing. The tyres are much more difficult to handle and buff.

Repairs are limited to very specific tolerances. Companies have to ensure their process doesn’t damage the body plies during buffing. There may be need to replace breaker belts and perform other specialised repairs.

Each stage of production must comply with tightly controlled specifications. Every step of the process has to meet a specific specification.

“If the temperature drops by more than a set number of degrees during curing, then the tyre may no longer be acceptable. Aircraft retreading is governed by much stricter rules and regulations because of the nature of the application. You’re transporting people, so there can be absolutely no compromise on safety,” Burleson said.

Burleson identified shearography as the most significant technological advancement in aircraft tyre retreading.

“I would say the biggest advancement has been shearography. Another important development is laser engraving. Each time an aircraft tyre is retreaded, it’s assigned an ‘R level’ to ascertain the exact retread generation,” he said.

Laser engraving the sidewall makes record-keeping much more accurate compared with using stencils. Considerable progress has been made in buffing technology through computerised profiles too.

Automation is increasing in selected areas, although regulations limit the use of artificial intelligence as a trained human inspector must still verify and confirm the results.

SUSTAINABLE OPERATIONS

Aircraft retreading makes a significant contribution to sustainability by extending tyre life as each tyre is retreaded between three to six times.

The economics of cost savings and inexistence of Asian imports have also written an optimistic future for aircraft tyre retreading in US till now, but challenges are present for retreading machinery suppliers.

“We don’t make the machines ourselves but procure it from different countries for the US market. The challenge is providing equipment that meets our customers’ requirements and being able to service that equipment when it’s installed in their plants,” said Burleson.

However, he said that the broader retreading industry is undergoing consolidation. “In US, the East Coast is probably the largest market, followed by the West Coast, where the major population centres are,” he said.

Retreading plants are becoming larger in the TBR segment, processing higher volumes and adopting more automation. At the same time, smaller retreaders are finding it increasingly difficult to compete and many are going out of business.

Aircraft retreading is insulated from those market trends because of its unique business model.

Summing up the sector, Burleson reiterated that aircraft tyre retreading should not be viewed in the same way as commercial tyre retreading.

“The main thing people need to understand is that aircraft retreading is a speciality market. Although the process follows many of the same basic steps as commercial tyre retreading, it’s performed under much stricter controls because of the critical nature of its application. It’s not something that anyone can simply enter. It’s a highly specialised industry. Even though it’s still retreading, it shouldn’t be viewed in the same way as the normal commercial TBR market,” he noted.