Tire Companies Develop New Weight Reduction Technologies by Improving Materials

The main theme of tire research and development is the reduction of rolling resistance. For this reason, companies are focusing on the development of lighter tires. In recent years, new concepts have also been introduced that take into account the connectivity and charging of electric vehicles. Weight reduction is a particular focus of tire manufacturers in order to meet OEM needs for weight reduction, improve fuel efficiency of conventional vehicles, and extend the cruising range of BEVs. In July 2019, Toyo Tires unveiled a tire that was about 4kg lighter than the previous model. The amount of rubber used was reduced by increasing its strength using a technique to uniformly disperse the cross-linking points of the polymer. In September of the same year, Bridgestone announced Enliten, a tire weight reduction technology. By adopting a tire structure that equalizes the tire contact pressure, the company succeeded in reducing weight by about 20%. In October of the same year, Yokohama Rubber unveiled the Ultra Lightweight Concept Tire, a lightweight tire concept that uses high-strength components and uses stress control on the tire components at the Tokyo Motor Show. Responding to CASE promoted by OEM is also positioned as one of the important items by tire makers in parallel with the development of weight reduction technology. In response to electrification, Bridgestone is participating in the research and development of in-wheel motors and roadside wireless power feeding, a joint project with The University of Tokyo. Bridgestone is in charge of developing tires that do not interfere with the power supply from the road surface. The technology was introduced at the Tokyo Motor Show in 2019. Yokohama Rubber and Sumitomo Rubber Industries are also developing connected services using tire pressure monitoring sensors (TPMS). By collecting TPMS air pressure and temperature data in the cloud and allowing the users to check their vehicle’s status, it is possible to respond quickly to emergencies such as punctures and increase the efficiency of tire maintenance. In the future, tire manufacturers will collect and utilize not only tire pressure and temperature data but also tire wear and road surface data, as well as develop predictive maintenance functions using AI. Such data can contribute to improved vehicle operation efficiency for car sharing and fleet services by improving vehicle safety and optimizing maintenance timing.

Next-generation Tires: Recent Major Technical Trends

Weight Reduction

・In September 2019, Bridgestone developed Enliten, a lightweight technology for reducing CO2 emissions by lowering the weight of tires. – Improves the internal shape of the micro-groove (sipe) near the center of the tread. Change to a three-dimensional shape instead of a simple groove. The behavior of the pattern block was optimized. – Utilizing the latest simulation, the pressure applied to the tire’s contact surface was made uniform. – Using sipe and grounding surface shape technology, handling and wear resistance were maintained, while the number of components used in tires was reduced. – Tire size 225 / 40R18: Weight was reduced by 20% compared to the previous model (about 2kg on a weight basis). Reduced rolling resistance by 30%. – Through Enliten, Bridgestone says it can reduce CO2 emissions caused by tires by 30% by reducing resources used and lowering rolling resistance. – The company plans to commercialize it after 2020 and intends to expand its size lineup.

Yokohama Rubber

・Yokohama Rubber introduced a lightweight tire technology called Ultra Lightweight Concept Tire at the Tokyo Motor Show in October 2019. – The lightweight and fuel-efficient BluEarth-air EF21 tire (25% lighter than the previous model), which was announced in 2017, has been further improved. It is approximately 50% lighter than the previous model. – The threads and sidewalls were made thinner. – Looking at the tread design, the internal belt, which is the skeletal material, has been changed from conventional steel to high-strength aramid, ensuring the same strength and rigidity as conventional tires. – For the sidewall design, stress analysis was used to create a shape with an advantageous angle to reduce load. The thickness of the tire was reduced by changing the rubber material. The carcass, which is an inner component, was replaced with a high-strength material. – The Ultra Lightweight Concept Tire technology analyzes tire air resistance in parallel with weight reduction. Toyota is aiming to improve fuel efficiency by reducing the running resistance of the entire vehicle by lowering air resistance of the tire by using fins.

Toyo Tires

・Toyo Tires (formerly Toyo Tire & Rubber) unveiled a lightweight technology using improved material structure at the Automotive Engineering Exposition 2019 Nagoya in July 2019. – Used simulation to improve material structure. Introduced high-elongation and high-strength rubber compounding design. – Introduced cross-linked chain polymer to the rubber material. – Conventional polymers have variations in arrangement, such as cross-linking points concentrated in certain parts. In the newly developed material, the positions of the cross-linking points are adjusted and distributed evenly. – By uniformly dispersing the cross-linking points, the strength and elongation of the rubber are improved by a factor of two compared to conventional products. As a result, the amount of rubber used in the tire can be reduced which in turn leads to lower tire weight. – Weight has been reduced by about 4 kg (per unit) compared to the previous generation. – The same technology is also intended to be used for abrasion improvement.

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