Rubber in automotive a balancing act for a new age

AKRON—With a global value of about $57.4 billion in 2024, the automotive rubber market’s future is as bright as the challenges are daunting.

Rubber use in both tire and non-tire automotive applications is expected to rise through 2030, with tire rubber set at 2.5 percent CAGR over the next five years; and EV tire rubber set at 13.5 percent through 2030, according to a recent report from Smithers, a global testing and consulting firm based in Northeast Ohio. 

Rubber in automotive (RIA)—including non-tire applications—is expected to reach $84 billion by 2033, according to the India-based IMARC Group.

“The growth in rubber consumption is being driven by shifts in the automotive industry, including increasing demand for sustainability, electrification, connectivity and autonomous driving,” Josh Guilliams, vice president of consultancy for Smithers, told Rubber News. “Both tire and non-tire rubber usage is expected to grow over the coming years.”

Such massive growth assumes that solutions will be met in material science for more sustainable, longer lasting tires, as well as more durable and flexible hose and sealing solutions for EV coolant functions.

“Seals in both internal and external applications tend to provide the largest opportunity for growth, considering the evolving design of vehicles,” Guilliams said, citing battery compartments and larger sunroofs. “In addition, dampening applications focused on reducing cabin noise and improving ride comfort given the realities of increased vehicle size and new EV platforms, will grow steadily.”  

RIA’s expected global increase in CAGR also assumes that a one-for-one, performance-equal, drop-in replacement will be found for virgin carbon black and 6ppd.

And the global increase assumes one other important variable: that consumers will pay for these measures, which will come with a cost.

“Many consumers have reported making purchasing decisions based on the sustainability of both products and brands,” Guilliams said. “However, some consumers do not factor sustainability into their decision-making and are especially unlikely to choose a sustainable option if it costs more than a more conventional competitor product.” 

In 2025, Smithers estimates that 20.7 million tons of rubber will be consumed by the tire industry. 

The firm forecasts that 23.8 million tons of rubber will be consumed to make tires by 2030.

According to Smithers, the fastest growing consumer of tire elastomers to 2030 is India with a CAGR of 3.5 percent, followed by China at 2.9 percent CAGR. 

North America comes in at a 2.8 percent CAGR to 2030, according to Smithers data.

“As tier one tire makers focus production on premium tires, India, followed by China, is taking the lead as high-volume tire producers, which accounts for their leading consumption of rubber for tires,” Guilliams said.

Rubbers that will be consumed most by the tire industry, according to the Future of Tire Raw Materials to 2030, include butyl rubber at 5.6 percent; polybutadiene at 5.1 percent; natural rubber at 4.2 percent; and solution-SBR at 4.1 percent.

“The strong growth of butyl rubber is due to tire makers’ increasing use of the material to reduce tire weight and improve fuel efficiency,” Guilliams said.

Polybutadiene is the second most common synthetic elastomer used in tires, due to the need for fatigue and aging resistance, where the material excels in tire sidewall compound

The automotive market today remains a mix of internal combustion engines and a range of powertrains for EVs, from plug-in hybrids to battery powertrains to fuel cell options, like hydrogen.

“Given the predominance of internal combustion engines still in the market, increased global demand for EVs has driven a greater need for a variety of specific applications,” Guilliams said. “While some of the basic applications are not new, EVs sometimes present some unique performance requirements.”

They include seals and gaskets around battery compartments that protect the battery from moisture and the elements.

And vibration dampening applications take on a new importance, as engine noise has been removed from the vehicle. 

“Dampening serves to reduce not only overall vibrations in the vehicle but also cabin noise,” Guilliams said. 

Thermal management systems within EVs use rubber hoses, seals, and gaskets that are now exposed to new varieties of coolant fluids. 

“If you’ve ever looked underneath an EV, the wire and cable bundles for connecting all electrical components and battery systems are extensive,” Guilliams said. “Wiring harnesses and shielding are used throughout to protect and guard against the elements. Insulating properties, abrasion and heat resistance are critical in these applications.” 

And outside of the vehicle, rubber remains critical for EV charging stations, providing environmental protection through weather-resistant seals and enhancing safety with flame-retardant gaskets.

“Silicone rubber also plays a vital role in thermal management, effectively dissipating heat from high-current charging processes,” Guilliams said.

With these tectonic shifts in RIA, the material testing world has had to adjust, Guilliams said.

“Material testing has had to adjust to both application-specific changes as well as challenges related to both sustainability and interactions with the environment,” he said. “On the application side, we’re seeing the use of more FKM materials for compatibility with new fluids.”

The magic triangle isn’t just confounding for material scientists trying to balance wet traction, abrasion resistance and rolling resistance.

There is another diabolical triangle, as consumers want a safer tire, a more sustainable tire and a cheaper tire.

“In some respects, EVs have somewhat reset the factors going into the magic triangle calculations for tire designers,” Guilliams said. “The extra weight of EV batteries and higher torque in electric motors put additional pressure on EV tires, which can increase the rate of tread wear and reduce the lifespan of the tire.” 

Even small increases in rolling resistance improvements can extend the range of an EV, 
Guilliams said. 

“Tire manufacturers are working to find a balance between wear resistance and product lifespan without compromising other important tire performance characteristics,” he said. 

Relative to ICE, EVs remain a relatively small percentage of the vehicles on the roads.

“With lower volumes, special tires designed for EV performance can’t generally benefit from the higher volume cost advantages of tires manufactured for the general range of vehicle types,” Guilliams said. 

Factor in sustainable materials to these dizzying calculations and manufacturers have even greater challenges.

As Guilliams notes, some filler materials are still in the development phase where performance is improving, but the capacity and volume is not quite there yet to support cost parity. 

One of the most urgent challenges facing the automotive industry is finding an alternative to 6ppd, an antiozonant used in tire manufacturing to prevent cracking and degradation. 

Studies at the University of Washington and other institutions have concluded that a transformational offshoot that occurs during tire wear, 6ppd-quinone, can be toxic to coho salmon and other aquatic life forms. 

However, a suitable alternative to 6ppd has yet to be commercialized.

The chemical is under an alternatives analysis study in California, assisted by the U.S. Tire Manufacturer’s Association, and possible alternatives have been whittled to seven.

“Considerable resources are going toward testing alternatives that deliver the same antidegradation performance without posing any risk to aquatic life,” Guilliams said. “These market demands bring the need for a more holistic approach to material choices for all rubber products going forward.”

According to Guilliams, any alternative to 6ppd must balance both consumer safety and environmental concerns.

But because of the urgency for a replacement, innovation cycles for tire manufacturers are being pushed faster. 

“This could simply be for market reasons but also could be due to urgent innovation requirements, like 6ppd,” he said. “Material modeling and big data are playing a much larger role in evaluating options in parallel with any physical testing or mixing that needs to occur. 

“Models for component assemblies, tires and full vehicles are increasing the speed of design validation.”

Tire compound additives and fillers are becoming more sustainable, but by and large they have not achieved a commercialized level yet.

“A front runner has not emerged at this point, but pyrolysis carbon black is potentially farther along from a commercial standpoint,” Guilliams said. “There are tire applications for which these technologies can be more readily adopted than others, in terms of the tire compounds. If someone can make a sustainable carbon black that can provide equal or better wear performance than a tread carbon black, that will make the biggest difference.”  

A range of macro-trends are pushing the greener tire.

Internally for companies, sustainability initiatives and regulations in various markets are driving innovation, while other factors include competitive differentiation and better supply chain management, both also seen as incentives.

“Like any new technology, however, performance balanced with overall cost to the consumer and regulatory requirements must be considered given the increasingly competitive nature of the tire industry,” Guilliams said. “So much progress has been made to date, and there are still many developments in process. 

“Given the truly global nature of the tire and automotive industry, regulatory pressures in some markets, and the amount of research and development already invested into sustainable materials and practices, this development will continue forward.”

The magic triangle in tire making continues to confound.

As the perfect balance between tire wear, grip and rolling resistance remains a moving target, the introduction of EVs is pushing the envelope even further.

“EV requirements demand more from the tire,” Guilliams said.

And successes are being realized. 

“Higher surface area silica supports better rolling resistance performance as well as lightweighting,” Guilliams said. “More graphene technology and carbon nanotubes have been used to provide better reinforcements, reduce overall weight and give better rolling resistance. 

“High-performance resin technologies are being introduced to improve grip performance. Some of these resins could provide options for improved sustainability.” 

To reach these solutions, manufacturers are using more thermoplastic polyamide elastomers and TPVs, especially in hose systems.

“TPAs and TPVs provide superior flexibility and durability and are lightweight, all desirable attributes for cooling applications,” Guilliams said.

And hydrogen fuel cells remain top-of-mind for many suppliers to tier one manufacturers.

“Hydrogen’s small molecular size allows it to permeate through many conventional sealing materials, leading to leakage risks in both transport and storage systems,” Guilliams said. “The wide temperature ranges encountered in hydrogen applications, from cryogenic liquid storage to high-temperature fuel cell operation, require seals that maintain their performance across extreme conditions. 

“High-pressure storage and transport further compound these challenges, requiring seals capable of withstanding immense stress.” 

Guilliams noted that chemical compatibility also is necessary.

“In thermal management systems, understanding the conductivity of the material as it interacts with specialized coolants is critical,” he said. “Contact with EPDM could potentially leach ions and change the conductivity of the coolant being used.”