Tire noise is the sum of many things, but it can also be influenced

Two types of tire noise

Tire noise heard inside the car consists of airborne noise as well as structure-borne noise. Airborne sound travels to the interior from outside through the body of the car. Structure-borne noise, on the other hand, is transferred to the interior along the car's structures.

The main source of airborne noise is the tire's contact with the road surface, such as the crunch of sand or rattle of studs. Structure-based noise, on the other hand, occurs when the rotation of a tire against the road causes vibrations in the tire. The air inside the tire is hard, usually at a pressure of 2–3 bar, which allows the air space to vibrate and rumble. The noise is transmitted through the car's axles and suspension to other parts of the structures and finally to the interior and the driver. Especially at higher driving speeds, structure-borne noise is emphasized, as the sound of car-road contact is no longer audible through other driving noise.

Tire noise is dependent of many different things

The intensity of tire noise depends on the whole and is affected by many things such as the degree of tire wear, the structure of the vehicle's chassis and the roughness of the road. This makes simulating tire noise challenging, as it is mainly transmitted through the vehicle's structures and varies from vehicle to vehicle. The same tire can be very quiet on one car model, but surprisingly noisy on another. For example, in otherwise quiet EV’s tire noise can be distinguished better, which can create the illusion of louder tires. A noisier tire is also often chosen for an EV due to its other characteristics. For example, tires with lower rolling resistance are preferred in electric cars to ensure a better range, but at the same time, a tire with low rolling resistance absorbs less energy that is reflected into tire noise, and results into  more tire noise.

Tire noise can be influenced by product development and the right tire choice

Tire noise can be reduced somewhat by making the right tire noise. Typically, tires with larger rims have a lower sidewall, which means that tire noise is not absorbed as much and may be transferred more easily through the chassis to the driver. In winter tires, the choice is often between non-studded and studded tires. The studs strike the road surface and cause a vibration that travels to the tire structure, rim and further to the vehicle's axles and body. The intensity and quality depends on many different factors, such as the number of studs, protrusion, size, tire construction, stud placement, tread pattern, rubber compounds used, and the road surface.

On the other hand, tire noise can also be reduced in tire development phase through material choices, such as a softer tread rubber compound and noise-cancelling foam, which reduces noise inside the car. For example, Nokian Tyres SilentDrive™ tires utilize innovative noise-cancelling foam, which reduces noise by up to seven decibels of the resonant frequency of the tire's airspace. The resonance is one of the many sounds that can be sensed inside a car, classified as structure-borne noise.

Reducing both rolling resistance and tire noise are both an important part of Nokian Tyres' product development. However, the most important thing is the tire’s safety such as wet grip and ice grip. The tread, size, rolling resistance and studs all contribute to not only tire noise but also the tire’s driving characteristics. First and foremost, drivers should always choose the most suitable and safest tire for their usual driving conditions.