Tyres do not typically carry the weight of our vehicles but it is only the air inside them does. There are three basic elements which determine the load capacity of a tyre namely, the size of the air chamber formed between the tyre and wheel, the strength provided by the engineering construction of tyre to hold air pressure, and the amount of air pressure actually in the tyre.

Most flat tyres or zero pressure air  are the result of slow leaks that go unnoticed and allow the tyre's air pressure to escape over time (Fig.1). Therefore, monitoring tyre air pressure in real-time is extremely important. Fortunately, in these days we practically have such devices inbuilt in tyre, called, Tyre Pressure Monitoring System or TPMS, Fig.2. Run Flat Tyres (RFT) are typically designed passenger car tyre or light truck tyres or SUVs to run even when they are flat  or when there is zero inflation pressure. It is more of a safety issue - it's design allows you to continue driving in deflated condition to a point were you can safely get the tyre changed or repaired. To all RFT, therefore, it is was required to fit in TPMS system (Fig.2) to indicate driver that the tyre is running with low pressure or tyre is failed and is under zero pressure now.

Tyre pressure sensor (pressure transmitter) converts the physical quantity 'tyre pressure' into an industry-standard signal , that enables the driver if the tyre pressure is becoming low or the tyre has already failed during driving (Fig.2). Mandates for TPMS technology in new cars have been continued to proliferate in the 21st century in Russia, the EU, Japan, South Korea and many other Asian countries. As of November 2014, the above fitment rate stands had been to ~ 54% of passenger cars.

 

Tyre pressure has profound influence on vehicle safety and efficiency. Tyre-pressure monitoring (TPM) was first adopted by the European market as an optional feature for luxury passenger vehicles in the 1980s. The first passenger vehicle to adopt TPM was the Porsche 959 in 1986, using a hollow spoke wheel system. In 1996 Renault used the Michelin PAX system. In the United States, TPM was introduced by General Motors for the 1991 model year for the Corvette in conjunction with Goodyear run-flat tyres. The system uses sensors in the wheels and a driver display which can show tyre pressure at any wheel, plus warnings for both high and low pressure (Fig.2). It has been standard on Corvettes ever since.

The dynamic behavior of a pneumatic tyre is closely connected to its inflation pressure. Key factors like braking distance and lateral stability require the inflation pressures to be adjusted and kept as specified by the vehicle manufacturer. Extreme under-inflation can even lead to thermal and mechanical overload caused by overheating and subsequent, sudden destruction of the tyre itself. Additionally, fuel efficiency and tyre wear are severely affected by under-inflation. Tyres do not only leak air if punctured, they also leak air naturally (air permeability), and over a year, even a typical new, properly mounted tyre can lose from 3 to 9 psi, roughly 10% or even more of its initial pressure.

Maintaining proper tyre inflation is essential to vehicle handling, overall tyre performance, and load carrying capability. A properly inflated tyre will reduce tread movement, reduce rolling resistance, and increase water dispersion. Reduced tread movement gives the tyre a longer tread life. Reduced rolling resistance, the force required to roll a loaded tyre, results in increased fuel efficiency. Increased water dispersion decreases the possibility of hydroplaning. Both over-inflation and under-inflation can cause premature tread wear and possible tyre failure. Over-inflation can result in decreased traction and the inability to absorb road impact. Overinflated tyres will show premature wear in the centre of the tread. On the other hand, under inflation will cause sluggish tyre response, decrease fuel economy, excessive heat buildup, and tyre overload. An under inflated  tyre will show premature wear on both outside shoulders (Fig.3).

 

The European Union reports that an average under-inflation of ~ 6psi ,  produces an increase of fuel consumption of 2% and a decrease of tyre life of 25%. The European Union concludes that tyre under-inflation today is responsible for over 20 million liters of unnecessarily-burned fuel, dumping over 2 million tones of CO₂ into the atmosphere, and for 200 million tyres being prematurely wasted worldwide. In 2018, a field study on TPMS shows that TPMS fitment reliably prevents severe and dangerous under-inflation and hence yields the desired effects for traffic safety, fuel consumption and emissions. The above study also showed that there is no difference in effectiveness between dTPMS and iTPMS and that the TPMS reset function does not present a safety risk.

The Tyre Pressure Monitoring System (TMPS) is an electronic system in the vehicle that monitors tyre air pressure and alerts the driver when it falls dangerously low. This system involves a pressure sensor (Fig.4) fitted in tyre air filling valve. However, a given TPMS system can only work with compatible sensors in the tyres.  

 

TPMS notifies on vehicle dash board when vehicle’s tyre pressure is low or is going flat and this help to maintain proper tyre pressure (Fig.2). TPMS can directly or indirectly, increase vehicle safety on the road by improving your vehicle’s handling, decreasing tyre wear, reducing braking distance and bettering fuel economy. The significant advantages of TPMS are summarized as follows:

• Fuel savings: For every 10% of under-inflation on each tyre on a vehicle, a 1% reduction in fuel economy will occur. In the United States alone, the Department of Transportation estimates that under inflated tyres waste 2 billion US gallons (7,600,000 m³) of fuel each year.

• Extended tyre life: Under inflated tyres are the major cause of tyre failure and contribute to tyre disintegration, heat buildup, ply separation and sidewall/casing break downs. Further, a difference of 10 psi in pressure on a set of duals literally drags the lower pressured tyre 2.5 metres per kilometre (13 feet per mile). Moreover, running a tyre even briefly on inadequate pressure breaks down the casing and prevents the ability to retread. It is important to note that not all sudden tyre failures are caused by under-inflation. Structural damages caused, for example, by hitting sharp curbs or potholes, can also lead to sudden tyre failures, even a certain time after the damaging incident. These cannot be proactively detected by any TPMS.

• Improved safety: Under-inflated tyres lead to tread separation and tyre failure, resulting in 40,000 accidents, 33,000 injuries and over 650 deaths per year only in USA. Further, tyres properly inflated add greater stability, handling and braking efficiencies and provide greater safety for the driver, the vehicle, the loads and others on the road.

 

• Environmental efficiency: Under-inflated tyres, as estimated by the Department of Transportation, release over 26 billion kilograms (57.5 billion pounds) of unnecessary carbon-monoxide (CO) pollutants into the atmosphere each year in the United States alone.

A TPMS reports real-time tyre-pressure information to the driver of the vehicle, either via a gauge, a pictogram display, or a simple low-pressure warning light (Fig.2).  

TPMS can be divided into two different types – direct (dTPMS) and indirect (iTPMS). TPMS are provided both at an OEM (factory) level as well as an aftermarket solution (replacement market). TPMS is increasing consumer demand for avoiding traffic accidents, poor fuel economy, and increased tyre wear due to under-inflated tyres through early recognition of a hazardous state of the tyres.

A sensor based TPMS has a pressure monitoring sensor fixed inside the wheel and tyre  assembly(Fig.5). This is usually clamped to the wheel and constantly monitors the internal pressure of the tyre . This information is relayed to a receiving unit on the vehicle body which is connected to a processing unit in the electronics system of the vehicle. This alerts the driver to a loss in tyre pressure.

 

There are two different types of systems being used today: Direct TPMS and Indirect TPMS. Direct (dTPMS) uses a sensor mounted in the wheel to measure air pressure in each tyre. When air pressure drops 25% below the manufacturer’s recommended level, the sensor transmits that information to the computer system of car and triggers your dashboard indicator light (Fig.2).

 

Indirect (iTPMS) works with Antilock Braking System’s (ABS) wheel speed sensors. If a tyre’s pressure is low, it will roll at a different wheel speed than the other tyres. This information is detected by the computer system of car , which triggers the dashboard indicator light (Fig.2). The purpose of the TPMS is to alert you when tyre pressure is too low and could to create unsafe driving conditions. If the light is illuminated, it means your tyres could be underinflated, which can lead to undue tyre wear and possible tyre failure.

Direct TPMS

Direct TPMS (dTPMS), is a directly measuring hardware-based systems. They could be fitted in each wheel, most often on the inside of the valve (Fig.6), there is a battery-driven pressure sensor which transfers pressure information to a central control unit which reports it to the vehicle's instrument cluster or a corresponding monitor. Some units also measure and alert temperatures of the tyre as well.

These systems can identify under-inflation in any combination, be it one tyre or all, simultaneously. Although the systems vary in transmitting options, many TPMS products (both OEM and aftermarket) can display real time tyre pressures at each location monitored whether the vehicle is moving or parked. There are many different solutions, but all of them have to face the problems of exposure to hostile environments. The majority are powered by batteries which limit their useful life.  A direct TPMS sensor consists of the following main functions requiring only a few external components, that is mounted to the valve stem inside the tyre:

 

• Pressure sensor
• Analog-digital converter
• Microcontroller
• System controller
• Oscillator
• Radio frequency transmitter
• Low frequency receiver
• Voltage regulator (battery management)

 

InDirect TPMS

Indirect TPMS (iTPMS)  uses to detect the differing speed of revolution of a wheel with a reduced circumference, caused by a reduction in tyre pressure . There may be  dashboard icons for low pressure warning icon  or system failure icon (Fig.2). This system uses the ABS  or the Antilock Braking System of the vehicle to monitor the rotation speed of the individual wheels. If a deflation of a tyre occurs the resulting increase in wheel speed triggers the TPMS and advises the driver accordingly (Fig.7).

Advantages of the ABS based system include the fact that the system uses technology and equipment that is already fitted to the vehicle. Also there are no sensors fitted inside the wheel/tyre assembly which makes the tyre fitting process easier than the sensor based systems.

Dr Samir Majumdar, Rubber Consultant (India & Asia pacific), has served in leading tyre companies like JK Tyre, Kyoto Japan Tire, among others. He was technical and R&D head (Asia Pacific) in ExxonMobil. He has authored several research papers and technical books. smajumdar501234@yahoo.co.in

Zeon Corporation has announced the development of Nipol BR1300, a novel hydrophilic styrene butadiene rubber (SBR) for winter tyres. Synthesised with a polybutadiene rubber base, the material delivers unprecedented hydrophilicity for tyre applications. Commercial production began in May 2025 at Zeon’s Tokuyama plant in Yamaguchi Prefecture.

As part of its strategic portfolio optimization, Zeon plans to phase out low-profitability products like ESBR-1 and NBR latex by 2026. However, it will continue manufacturing high-margin products, including ESBR-2, nitrile butadiene rubber and solution SBR. This shift underscores Zeon’s focus on advanced, value-driven rubber solutions.

Covestro India has entered into a strategic collaboration with CSIR-National Chemical Laboratory (NCL) through an innovative CSR initiative focused on developing sustainable upcycling technologies for polyurethane waste. This partnership aims to overcome existing recycling limitations by transforming discarded polyurethane materials into valuable chemical feedstocks, potentially revolutionising the material's circular economy.

This collaboration underscores both organisations' commitment to environmental innovation, leveraging NCL's advanced research infrastructure and Covestro's market leadership to address critical gaps in plastic circularity. Current polyurethane recycling methods, predominantly mechanical with some emerging chemical processes, face substantial challenges including material degradation, high energy consumption and hazardous byproduct generation. The project seeks to develop commercially viable chemical recycling solutions that maintain material integrity while minimising environmental impact.

Polyurethanes, widely used in furniture, automotive parts and insulation, present unique recycling difficulties due to their complex molecular structure. Most end up in landfills after use, creating significant sustainability challenges. By combining Covestro's industrial expertise with NCL's seven decades of chemical research excellence, the partnership aims to create breakthrough upcycling technologies.

Avinash Bagdi, Director & Head of Sales & MD Solutions India & Projects – Tailored Urethanes, said, "This partnership strengthens our commitment to finding innovative solutions for polyurethane waste and directly supports Covestro's vision of becoming fully circular. By developing effective methods to upcycle polyurethanes, we're taking concrete steps towards creating a more sustainable future in line with our corporate vision of driving the transition to a circular economy."

Dr Ashish Lele, Director of NCL, said, "CSIR-National Chemical Laboratory is excited to partner with Covestro (India) in this groundbreaking initiative to develop novel chemical upcycling methods for polyurethane waste. The conventional and electrochemical strategies we're developing address the critical limitations of current recycling technologies and align perfectly with our shared vision of a circular economy. This collaboration represents a significant step towards sustainable plastic management in India and globally, with potential to transform polyurethane waste into valuable chemical resources."

Zeon Corporation has begun building a pilot facility at its Tokuyama Plant in Shunan City, Yamaguchi Prefecture, to test a new method for efficiently producing butadiene from plant-derived ethanol. The demonstration plant, expected to start operations in 2026, will supply butadiene for manufacturing trial batches of polybutadiene rubber, bringing the company closer to commercialising this sustainable production process.

This project is a key part of a joint initiative between Zeon and The Yokohama Rubber Co., Ltd. to develop eco-friendly methods for producing butadiene and isoprene from renewable sources, with full-scale adoption targeted for the 2030s. Under the collaboration, Zeon will produce butadiene rubber at the new facility, while Yokohama Rubber will use the material to create experimental tyres and conduct performance testing. The data collected will help refine the technology ahead of larger-scale trials. The companies aim to finalise the production process by 2030 using an expanded pilot plant, with plans for industrial-scale commercialisation by 2034.

A ceremonial groundbreaking event took place on 10 July 2025, with 33 attendees, including local government officials from Yamaguchi Prefecture and Shunan City, construction partners and Zeon executives such as Chairman Kimiaki Tanaka and Tokuyama Plant Manager Akira Honma. The gathering included traditional safety prayers for the construction phase, marking the official start of this sustainability-focused industrial project.

Continental is increasing its use of renewable and recycled materials in tyre production, aiming to exceed 40 percent by 2030 while maintaining high safety and performance standards. In 2024, these materials accounted for 26 percent of tyre composition, with a projected 2-3 percent increase in 2025. Key to this shift are carbon black and silica – essential fillers that enhance durability, grip and braking performance.

Silica, a critical component for optimising grip and minimising rolling resistance, is traditionally derived from quartz sand. However, Continental now obtains silica from rice husks, an agricultural by-product of risotto rice production. This innovative approach not only repurposes waste but also requires less energy than conventional methods. Partnering with manufacturers like Solvay in Italy, Continental integrates rice husk-derived silica across its entire tyre portfolio. Silica has been a game-changer in tyre technology for decades, significantly improving safety and energy efficiency. Its use in tread compounds has contributed to a nearly 50 percent reduction in braking distances while also lowering rolling resistance, thereby reducing fuel consumption and CO₂ emissions.

Carbon black, another vital material making up to 20 percent of a passenger car tyre's weight, is being sourced through sustainable alternatives. Continental employs three innovative methods: bio-based carbon black from tall oil (a paper industry by-product), recycled carbon black from pyrolysis oil derived from end-of-life tyres and a direct recovery process that extracts carbon black from used tyres via pyrolysis. The company collaborates with suppliers like Orion Engineered Carbons and Tokai Carbon, utilising different carbon black variants tailored to specific tyre components, such as sidewalls and treads. Through the mass balance approach, Continental substitutes fossil-based raw materials with bio-based or recycled alternatives without altering existing production processes.

Additionally, Continental has partnered with Pyrum Innovations to advance tyre recycling through pyrolysis, a process that recovers carbon black from end-of-life tyres for reuse. While currently applied in forklift tyres, efforts are underway to adapt this recycled carbon black for broader tyre applications, ensuring compliance with performance and safety standards. These initiatives underscore Continental’s dedication to sustainable innovation, demonstrating how eco-friendly materials can enhance both tyre performance and environmental responsibility across the value chain.

Jorge Almeida, head of Sustainability at Continental Tire, said, “Innovation and sustainability go hand in hand at Continental. Using silica from the ashes of rice husks in our tyres shows that we are breaking completely new ground – without compromising on safety, quality or performance.”