Tire Noise & Quiet Tire Tech

1. From "Ignored" to "Core Concern": The Historic Transformation of Tire Noise

Throughout the long history of the automotive industry, tire noise has long been overlooked. In the early days, the roar of fuel-powered vehicles' engines, the mechanical noise of transmission shifts, and the vibration of the chassis and drivetrain combined to constitute the primary sources of vehicle noise.

Back then, the noise generated by tire friction against the road was drowned out by these more intense sounds. Even though there were differences in the quietness performance of different tires, consumers had difficulty directly perceiving it, and quietness naturally did not become a core criterion in tire selection.

However, with the automotive industry's transition toward "electrification, intelligence, and quietness," this situation has been completely changed. Tire noise has moved from the "backstage" to the "front stage," becoming a key factor affecting the driving experience and forcing the entire tire industry to embark on a major effort in developing quieting technology.

2. Upgrading the Quietness of Fuel-Powered Vehicles: The Direct Cause of the Emerging Tire Noise Problem

The comprehensive improvement in vehicle quietness is the direct cause of the increasing concern for tire noise. In recent years, both high-end gasoline-powered vehicles and mainstream family cars have been investing heavily in soundproofing: more sound-insulating padding has been added to the body, windows have been upgraded to double-laminated glass, soundproofing covers have been added to the engine compartment, and soundproofing panels have been installed on the chassis. These measures have taken vehicle noise control to new heights.

Data shows that ten years ago, the average interior noise level of mainstream gasoline-powered vehicles at 60 km/h was approximately 65 decibels. Today, the interior noise level of vehicles in the same class has generally dropped to 58-62 decibels, with some high-end models even achieving levels below 55 decibels, approaching the quietness of a library.

With this "low noise floor," tire noise has become dramatically more noticeable. Previously masked by engine noise, tire noise has now become the most noticeable source of interior noise. This "buzzing" or "rustling" sound is particularly disturbing at a constant speed, causing fatigue over extended periods and significantly impacting ride comfort.

3. The Popularization of Electric Vehicles: Pushing Tire Noise to the Forefront

The increasing popularity of electric vehicles has further brought tire noise to the forefront. Unlike traditional fuel-powered vehicles, electric vehicles lack an engine as a core noise source. The noise generated by the motor is extremely low, even negligible at low speeds.

This makes tire-to-ground friction noise the primary noise source in electric vehicles, and its impact is even more significant. Test data shows that at the same speed and road conditions, tire noise levels in electric vehicles are 3-5 decibels higher than those in traditional fuel-powered vehicles. This gap widens further at higher speeds. For electric vehicle users seeking an "ultimately quiet" driving experience, tire noise has undoubtedly become a significant shortcoming that affects vehicle satisfaction.

At the same time, as countries tighten vehicle noise emission standards, electric vehicles face even higher demands for noise control. For example, the EU mandates that electric vehicles emit warning sounds at low speeds to ensure pedestrian safety. However, at normal speeds, both interior and exterior noise levels must meet stricter limits. This policy has also driven tire companies to invest in quieting technology research and development.

4. Multi-Dimensional Breakthroughs: Tire Companies' Quieting Technology R&D Path

Faced with the growing demand for quieter tires, tire companies have stepped up their R&D efforts, exploring breakthroughs in quieting technology across multiple dimensions, including materials, structure, and pattern design, driving the continuous upgrade and iteration of quiet tire products.

(I) Material Innovation: Optimizing Rubber Formulas to Enhance Shock and Noise Reduction

In terms of material R&D, tire companies are optimizing rubber formulas to improve the shock and noise reduction performance of tires. Traditional tires primarily use base materials such as natural rubber and styrene-butadiene rubber. While these materials offer excellent wear resistance and grip, they suffer from significant shortcomings in quietness.

Many companies are now developing and applying new polymer composite materials. For example, they incorporate special sound-absorbing materials or elastomers into rubber formulas. These materials effectively absorb the vibration energy generated by tire-road friction, reducing noise generation and transmission.

For example, Michelin's "Quiet Technology Rubber Formula" incorporates highly dispersed silica, which not only improves wet grip but also reduces tire noise by dispersing friction stress. Goodyear has developed "SoundComfort" technology, which incorporates a special foam insulation layer inside the tire to effectively absorb airborne vibration noise, reducing interior noise by 2-3 decibels.

(II) Structural Optimization: Reducing Vibration and Shortening Noise Transmission Paths

In terms of structural design, tire companies are optimizing the tire carcass structure and tread profile to reduce noise transmission paths. Traditional tire carcasses have a relatively simple structure, and the transition area between the tread and sidewall is abrupt, which can easily generate significant vibration and noise during driving.

Many silent tires now utilize an "asymmetric carcass structure." By adjusting the carcass' cord layout and number of layers, this achieves a more uniform stress distribution when the tire is under load, reducing vibration. Furthermore, optimized tread profiles, such as curved or variable-section treads, ensure a more uniform contact area with the ground and a more balanced distribution of contact pressure, thereby reducing friction noise.

In addition, some tires feature "silent grooves" on the sidewalls. These grooves guide air flow, reducing turbulent air noise generated during rolling, further enhancing the quieting effect.

(III) Pattern Innovation: Breaking Resonance and Reducing the Effect of Noise Superposition

In terms of pattern design, tire companies are innovating in tread patterns and arrangements to break the "resonance effect" of noise and reduce the superposition of noise. Tire pattern is a key factor influencing tire noise. Traditional tires often use a regular, symmetrical design. During driving, the tread blocks generate periodic impact noise when they come into contact with the ground. These noises have similar frequencies and are prone to resonance, leading to noise amplification.

To address this issue, silent tires commonly utilize an asymmetric tread design and a variable-pitch tread arrangement. The asymmetric tread design divides the tread into two areas: an inner and outer tread. The inner tread prioritizes quietness and drainage, featuring wider transverse grooves and smaller blocks. The outer tread, on the other hand, prioritizes grip and wear resistance, featuring wider blocks and denser longitudinal grooves. This functional division of labor between these areas ensures performance while reducing noise.

The variable-pitch tread arrangement adjusts the size and spacing of the tread blocks to disperse the frequency of the noise generated when they contact the ground, preventing resonance and effectively reducing overall noise levels.

5. Technological Empowerment: Advanced Testing and Simulation Accelerate R&D

In addition to technological research and development, tire companies are also utilizing advanced testing methods and simulation technologies to improve the R&D efficiency and product performance of silent tires. Many companies now have professional noise testing laboratories equipped with advanced acoustic testing equipment.

These labs are capable of simulating tire noise under various road conditions and driving speeds, and accurately measuring and analyzing tire noise levels.

Also, using computer simulation technology, companies can predict and optimize tire noise performance during the product design phase, reducing the number of physical prototypes produced, shortening the R&D cycle, and lowering R&D costs.

For example, Pirelli utilizes a "virtual acoustic simulation platform" to simulate the noise performance of different tread patterns, structures, and material options during the initial stages of tire design. Through comparative analysis, the optimal solution is selected, and then physical prototypes are trial-produced and tested, significantly improving the efficiency of quiet tire R&D.