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iON Completes the Intrinsic Value of EV - The Quietness

Emphasizing The Ideal State of Tires in the Age of EV

”Quietness” and “Eco-friendliness” are virtually synonymous with electric vehicles. But what does it really mean? Simply put, we are moving away from loud engine noises and environmental issues caused by exhaust gas. However, simply replacing the powertrain with an electric motor does not automatically yield such values of the electric vehicles. Achieving the true potential of the value of EVs requires a more in-depth and comprehensive approach to the research activities in the automotive industry.

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.

  • iON provides an optimal performance for which EVs are designed to deliver.

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.

A dedicated electric vehicle tire brand that embodies all the optimized performance requirements of EVs rooted in the Hankook Evolution Technology.

iON’s Technology, Silencing all Internal & External Noises
‘Sound Absorber Technology’

"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.

Tech A : Pattern Noise Reduction Technology
The pattern design that suppresses the screeching sound generated during sudden braking and directional changes

  • iON evo

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.

1. Reduce noise using knurling and side groove technology

① Knurling (lateral groove) technology

Placing the knurling (lateral grooves) structure on the main vertical grooves reduces the tire wind noise. Hankook Tire was able to reduce the noise by 0.8dB compared to the previous product

  • Anechoic Chamber Sound Power Measurement Condition (Tire Size: 225/45R17, Air Pressure: 2.13kg/cm^2, Evaluation Location: Hankook Technodome R&D Center, Anechoic Chamber Safety Walk Road surface)

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.

2. ‘Chamfer’ technology to reduce the noise when the tire hits the road

Similar to how sneakers make less of a sound than high heels do with the tiny top piece when walking, Chamfer technology that gently cuts the tread at an angle is introduced to tires.

This creates a much gentler contact with the road surface, reducing the noise during sudden stops and reducing the direction changes.

Tech B : Vibration Noise Reduction Technology
Do you hear a disturbing noise from the tires while driving safely?

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.

1. Block the cause of resonance with a design that prevents tire deformation

Based on the big data accumulated along with Hankook Tire's long history, the tire deformation was minimized with the optimal tire profile from the design stage.

Less deformation of the tire means the decreased deformation of air inside the tire, which leads to minimizing the resonant sound that stems from the vibration of the air.

2. Reduce vehicle noise by adjusting tire stiffness

The frequency control technology avoids the frequency range sensitive to vehicles. It reduces resonance by appropriately adjusting the reinforcement structure of soft or hard tires to minimize the interior noise.

3. Reduce vibration noise through the tire rubber mass control

It is a technology to tune the tire rubber mass for resonant noise mitigation, which reduces resonance while maintaining RR performance by optimally adjusting the rubber thickness.

Description of the actual vehicle measurement result conditions (Tire Size: 205/55R16H, Pattern: K125, Load: 409 kgf, Evaluation speed: 60km/h)

4. Reduce the tire-road surface noise through the application of a tire sound-absorbing material

A polyurethane sound-absorbing material that reduces the tire vibration noise is attached to the inside of the tire (inner liner) to reduce noise from the road surface by -9.2dB.

EV Driving Emotion is Near

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.