S U S T A I N A B I L I T Y

SUSTAINABLE VALUE CHAIN COLUMN

S U S T A I N A B L E V A L U E C H A I NWe are proactively advancing sustainability across the entire value chain—from raw material procurement to recycling—starting with motorsport tires.

Raw material &
Procurement

Expanding and Diversifying Renewable Resources

Achieved a recycled and renewable materials ratio of over 65%
Adoption of new recycled materials for the first time through co-creation：Recovered Carbon Black / Recycled Steel Cord

Development

With ENLITEN technology, delivering environmental performance while enabling solar cars to reach their full potential - through customization tailored for solar cars.

Achieves low rolling resistance, wear performance, lightweight, and puncture resistance

Production
&
Logistics

Low-carbon transportation: DHL's GoGreen Plus solution

Through the use of sustainable marine fuels, CO₂ emissions can be reduced by up to 85% across the entire lifecycle of fuel production, transportation, storage, and onboard use.

Use

Promote reducing the number of tires that are used during the event

(from 24 to 16).

Recycle

Promote recycling tires：End-of-life BWSC tires are planned to be recycled into a new high-quality rubber flooring for farms worldwide.

C O L U M N

Enhancing Sustainability Without Compromising Performance

In BWSC, vehicles travel 3,000 km across the Australian continent powered only by solar energy. Every bit of energy matters, and rolling resistance is one of the biggest factors in energy loss during driving. Since Bridgestone began supplying tires for BWSC, we have continuously refined every aspect—shape, structure, and materials—to minimize rolling resistance.
For the 2025 race, Bridgestone faced an even higher hurdle: increasing the use of recycled and renewable materials while expanding applicable materials, all without sacrificing performance. Supporting this challenge was the Tokai University Solar Car Team.

A Partner with Exceptional Technical Skill and Execution

The Tokai University team, composed of about 50 students, takes full ownership of everything—from design and assembly to driving.
According to Bridgestone’s tire development lead, Mr. Kibayashi:
“Each member’s skill level is extremely high, and it shows in the precision of the vehicle and driving techniques.”
Testing tires requires detecting minute differences in wear and resistance, often at the millimeter level. If the car’s alignment is off or driver skills vary, it becomes impossible to determine whether results stem from the tire or other factors. Tokai University’s precision and consistency make them an invaluable partner.
“Our tests demand long-distance runs under tight schedules. The team’s ability to meet these conditions with teamwork and adaptability is remarkable.”
Tokai University has earned Bridgestone’s trust as a partner that combines exceptional technical precision with strong team execution.

Rigorous Testing Under Pressure

Ahead of the 2025 challenge, verification tests were conducted on a dedicated course in Ogata Village, Akita Prefecture. To accurately measure tire wear, the team drove about 500 km per day for three consecutive days—totaling 1,500 km—under race-like conditions.

“Weather and temperature changes affected the road surface, and we had strict distance targets. Knowing these tires would be used by other teams added pressure. But Bridgestone trusted us, and we were determined to deliver,” said Mr. Ninomiya.
Maintenance lead Mr. Kimura added:
“We couldn’t afford any mechanical issues outside the tires. From sunrise, we worked as a team to prepare and follow the schedule precisely.”
After multiple rounds of testing, durability and stability were confirmed, and the tires were ready for the race.

Sustainability in Action

In August 2025, the BWSC took place in Australia. Tokai University finished 5th overall, proving that high performance can coexist with a high ratio of recycled and renewable materials.
Of the 34 teams competing, 32 chose Bridgestone tires. Many top European teams have also switched to Bridgestone, with some saying, “You can’t win without Bridgestone tires.”
“Developing tires that deliver stable performance under such extreme conditions is a major achievement,” said Mr. Kibayashi.
“BWSC is a stage where we can embody our commitment to sustainability through technology.”
Through this race, Bridgestone has shown that sustainability and performance can go hand in hand—a challenge that will continue to shape the future of mobility.

Combining Strengths for an Unprecedented Challenge

Bead wire is a vital component that anchors both ends of the carcass cord, forming the tire’s framework and securing it to the rim. The project was launched to use recycled steel in this bead wire.

T recalls, “We had a clear pathway for expanding the ratio of recycled and renewable resources in rubber and carbon black, but applying recycled steel was a high hurdle— the ‘final barrier.’ However, overcoming it would mean a significant step forward.”
He approached Nippon Steel, who had business dealings for wire rods used in commercial tires. Mr. N comments, “Steel is inherently highly recyclable, but recycling it to maintain the purity and strength required for tire bead wire was a very challenging task.”

Typically, steel is produced by reducing iron ore with coke in a blast furnace, which is Nippon Steel’s specialty. However, recycling steel primarily uses scrap iron, which contains rust and impurities. An electric arc furnace is better suited for melting scrap iron. As a partner with expertise in this area, Mr. N thought of Sanyo Special Steel within their group. Mr. K reflects, “Bead wire was an unknown field for us. It required much higher quality than our usual products, so we were unsure if it was even possible.”

Facing and Overcoming Issues from Scrap Iron

The biggest challenge was impurities remaining in recycled steel. “Impurities that wouldn’t be a problem in ordinary steel are unacceptable for bead wire. Since force is concentrated on thin wires, even minor contaminants can cause breakage,” says Mr. N.

A particularly troublesome impurity was alumina (aluminum oxide). During electric furnace processing, oxygen from rust and moisture in scrap iron enters, degrading quality. To remove oxygen, strong oxidizing aluminum is often added as a deoxidizer, but alumina forms as a result, which is problematic. “For thin wire like bead wire, even trace amounts of alumina are fatal. Alumina is harder than steel and causes cracking or wire breakage during drawing,” says T.

Sanyo Special Steel switched the deoxidizer from aluminum to silicon. Silicon is less prone to oxidation and leaves fewer impurities, but its deoxidizing power is weaker, and it was unprecedented for use in high-quality products. “We tested various conditions—timing, temperature, and more—to ensure sufficient oxygen removal with silicon,” Mr. K explains.

Another challenge was “gas.” Gas used in electric furnace melting can remain as tiny cavities in recycled steel. In thin bead wire, these cavities also cause cracking and breakage. The team repeatedly tested and analyzed conditions to prevent cavity formation.

“We discussed what was happening after every trial among the three companies. It was a cycle of doing, checking, and doing again,” says Mr. T.

By the end of 2022, they established operating conditions to overcome these challenges, finally achieving recycled steel of sufficient quality for tire use.

A Major Step Toward Sustainable Value Chains

The finished recycled steel was adopted in Bridgestone’s BWSC vehicle tires and delivered stable performance over the grueling 3,000 km race. “We proved that recycled steel from used tires can function adequately as bead wire,” says T.

This achievement is the first domestic case of reproducing a high-quality product previously only possible with blast furnaces, using steel derived from used tires and electric furnaces, which excel in scrap iron utilization. “Realizing a circular society is a critically important theme. From that perspective, this result is highly significant,” says Mr. N.
For Sanyo Special Steel, it also demonstrated new possibilities for electric furnaces. “Showing that electric furnaces can be used for bead wire is a big step. This experience will be aluable for future material development,” says Mr. K.
This initiative is an important step toward “sustainable value chains.” “It’s not just simple reuse—we want to expand ‘returning in high quality’ to even thinner steel cords beyond bead wire,” T concludes.