Kumho targets micro-mobility for NPT

When it comes to the development of nonpneumatic tires, Kumho believes the key to commercialization is starting small. Micro, even.

Kumho started its NPT journey back in 2000, and began developing the technology in 2016.

To date, Kumho has publicly released two concepts for airless tires: the BON (Birth on Nature) tire and the e-NIMF Airless Tire, both winners of iF Design Awards for 2018 and 2021, respectively.

The BON concept tire is what Kumho calls a "tire for the future."

It features a "Voronoi structure," according to the company's iF Design Award description, named for Russian mathematician Georgy Voronoi and his development of the Voronoi diagram. This diagram is a tessellation pattern found in nature—most notably in cells or the venation of leaves and insect wings.

To come to fruition, however, Kumho said this concept would require advancements in 3D printing technology and rubber powder materials capable of 3D printing.

The e-NIMF tire, on the other hand, is an airless tire concept designed specifically for passenger cars. This concept, Kumho said, has featured numerous spoke designs from 2017-21, including boomerang- and honeycomb-like structures, made of thermoplastic elastomers.

In its iF Design Award, the tire features a honeycomb-like structure—a design optimized for load support and ride comfort.

But there are drawbacks to pursuing such a design for passenger vehicles.

"Airless tires like these have separate spokes and wheels, and are structurally complex and heavy, making the tires more expensive," a Kumho spokesperson told Rubber News in an email. "Additionally, compared to pneumatic tires, they are lacking in terms of overall performance including vibration and ride comfort, so improvements are needed.

"So we decided that it was necessary to develop a new concept structure."

Today, the tire maker is focusing on micro-mobility, delivery robots and autonomous PBVs (platform beyond vehicles) in its pursuit of commercializing airless tire technology.

"In order to commercialize airless tires, our company is collaborating with autonomous driving companies and robot companies to jointly develop airless tires suited to the characteristics of mobility," Kumho said.

These characteristics include spoke durability, puncture resistance and ride comfort at low speeds, the company said.

For autonomous delivery robots, spoke durability will be particularly important as technology advances to allow them to climb stairs.

Much of what the company is working on in this sector is confidential, but Kumho did reference work with Mobinn—an autonomous driving spinoff of Hyundai Motor Co.—and its M3 delivery robot that can climb stairs.

The robot, being tested throughout South Korea, sported Kumho tires at the 2024 Consumer Electronics Show. The CES Innovation Award honoree can climb stairs due to Kumho's "squishy" airless tires, which feature bendable, lateral spokes.

"Airless tires for climbing stairs must have no problems with spoke durability or cracks due to repeated bending," Kumho said.

While Kumho is focusing on micro-mobility today, the company isn't limiting itself to this sector.

"Ultimately, we are targeting all categories where pneumatic tires can be replaced," it said. "To do so, we plan to first accumulate technology through the development of airless tires for low-speed vehicles and expand it to airless tire technology for high-speed PCR."

By 2027, Kumho anticipates exploring airless tires in high-speed technology, where it plans to develop an entirely new structure.

Kumho could not say for sure when it will bring any of its concepts to market, noting that vehicles equipped to support airless tires have yet to be commercialized, and laws and regulations surrounding airless tires have yet to be established.

It did say it hopes to supply airless tires to OEMs in 2026-27 by collaborating with companies developing micro-mobility and low-speed autonomous vehicles.

Richard Cunat, managing director at Kumho America Technical Center, said collaboration with OEMs is critical when bringing this type of technology to market.

"With this kind of technology, you almost have to partner with an auto manufacturer," he said, adding that this isn't work that should be done solely by tire companies. Much like working with pneumatic tires, NPT development is a group project.

"There's a process that we do to develop (pneumatic) tires," he said. "Throughout that process, (the tires are) being tested on the OEM manufacturer's vehicles. Once you get to the performance level that they require, then it goes to production."

The process works just the same when developing airless tires.

"If you just do it within the tire company, then you're trying to push or sell something onto an OEM, regardless of the size of a vehicle," he added. "It's a lot different when you do it collaboratively, when you figure out a solution together.

"It's tough to develop in a bubble … because the tires have to work as one unit with the vehicle," Cunat said. "The fit, the form, the function. All that."