Tires, the only component type with over 30,000 parts used in a vehicle that comes into contact with the road surface, require omnidirectional research and improvements to accurately address the needs of electric vehicles. At the center of it all lies highly complex acoustics research. If you are asking, “Aren't EVs naturally quiet?” then the answer would be Hankook Evolution Technology solution. / If someone asks, “Aren't EVs supposed to be silent?”, Hankook Evolution Technology, who created its own unique secret to low noise, will provide the solution.

Does the Quietness of EVs Bring the Worst of Tires and Road Noise?

Various sounds reach the drivers’ ears. 50% of the noise in a vehicle with an internal combustion engine comes from the powertrain, with the tire noise accounting for 30%. However, only 15% of the powertrain-induced noise makes up an EV, while the noise from tires constitutes 40%, and the wind noise at higher speeds takes approximately 30%. As EVs’ power originates from batteries, the absence of an internal combustion engine substantially reduces the operating noise. This causes the suppressed road and tire noises to be elevated in EVs even further.

Tire noise is generated when the tire comes into contact with the road surface. The noise produced from the vibrating air inside the tire during operation is called “resonant sound.” The resonant sound travels through the axle, which supports the vehicle’s weight and transfers the power to the tires. Once the resonant sound is activated, it tends to amplify at higher speeds. Furthermore, it could increase the fatigue of the driver and can interfere with safe driving. This makes the EV drivers prone to become more sensitive to noise. This is why the tires for EVs require both higher stability standards and a higher level of noise reduction.

"It's not easy to control all the tire noise generated while driving on various road surfaces.
To improve the major noise phenomena generated by EVs, sound absorbing materials and the low-noise pattern technology should be applied to provide the driver with the best driving sensibility."
Researcher Hyeon-seok Kang (NVH Project Team)

‘Sound Absorber Technology’ is Hankook Tire’s noise reduction technology that minimizes the tire noise. The technology is integrated into all stages of the tire design, including the structure and pattern designs and even through the noise test. Here we introduce Hankook Tire’s proprietary technology with two themes; pattern noise reduction and vibration noise reduction technologies.

You may have an experience when you cover your ears to a screeching sound while on the road. This high-pitched sound is generated at the contact patch of the tires when a vehicle is in an unstable condition, such as an accident. The answer to suppressing the unpleasant sound is in the tread pattern. Various types of patterns exist, from symmetrical V-grooves, zig-zag, deep grooves, to without any grooves, to deliver the specific performance required. In addition, pitch (rubber shape), knurling (horizontal groove), and the shoulder are combined to make a tire tread pattern. This means the research and expandability of the tire function through distinctive pattern designs is limitless. In this context, the pattern design technology developed by Hankook Tire for noise reduction is discussed below.

② Side Groove Technology

The side groove technology, in which the groove becomes wider towards the end, is applied to the shoulder of the tire to lower the pumping sound and maintain drainage.

A humming resonant noise. Once it happens, it takes considerable psychological and physical time to find the cause. Therefore, the technology to lower the resonance sound generation rate is essential for the resonance sound, and the attachment of a sound-absorbing material is used as a preventive measure. This improves the road noise transmitted over a particular range while maintaining the essential performance. However, it is challenging to completely prevent the resonance noise by attaching the sound-absorbing material alone. In response, Hankook Tire developed a technology that connects the sound-absorbing materials and adjusts tire stiffness, mass, and frequency.

iON, Hankook Tire's exclusive electric vehicle tire brand, is named after an ion, an electric atom. The brand identity contains the will to become a dependable and dedicated EV tire brand rising from its roots. In addition to the basic needs like stability, the brand will utilize AI-based road noise tests and pattern noise prediction tools, making the future expansion much more attainable.