Tire Noise Science

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3,100
Location
Idaho
Interesting article on tire noise:


Some excerpts:

...As you can imagine, the quietest tire is a smooth tread where no impact between the tread blocks and the road exists. The closer the tire pattern gets to a completely smooth tire, the quieter the tire gets. Tire manufacturers were able to reduce overall tire noise by 5 to 8 dB in the past 10 years. In some cases, modern tires have only 2-3 dB higher noise than smooth tires....

...Interior noise is transmitted inside of the vehicle through its structure and via air. Airborne noise consists of the progressive movement of mass particles (vibrations) and is transmitted in the form of soundwaves at the speed of sound to the vehicle cabin. Structure-borne noise is transmitted through the body of the vehicle through the tire. Exterior noise is transmitted outside through radiation and sound waves...

...The frequency of structure-borne and airborne noises shifts as the dominant inside noise as the result of changes in the vehicle’s speed. At lower frequency, normally at lower speeds, the structure-borne noise is the dominant type of noise. At a higher frequency range, normally at higher speeds, the airborne noise is the dominate type of noise....

...Structure-borne noise is normally around 160 Hz and is influenced by tire construction. Airborne noise is normally around 1,000 Hz and is influenced by a tire’s tread pattern...

...Tire noise is a very complex matter normally managed by a team of experts within tire companies who are experienced with NVH (noise, vibration and harshness). Because tire noise levels change internally and externally with the speed of the vehicle and the transfer through different sources, detecting and improving tire noise is difficult. However, with the advancement of prediction tools and a better understanding of noise sources, today’s tires are much quieter than their predecessors...
 
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447
Location
Cheshire, England
Low noise level is high on the list for me when choosing a new tire. Cars have become so quiet that tyre noise is the major source of noise at steady cruising speeds.
 
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488
Location
Canada
So the quietest tire is one with no treads and is perfectly smooth? How comes tire noise seems to go up as they wear down?
 
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3,839
Location
Somewhere in the US
Some things not covered in the article:

1) The road surface contributes to tire noise - sometimes a lot of noise. Even smooth tires on smooth surfaces generate noise, and smooth tires on normal road surfaces generate more noise than on smooth surfaces.

2) Tread patterns interact with the macrotexture of the pavement and produce some weird results. If you test a bunch of tires on one surface, then test on a different surface, you can get reversals.

3) Tires tend to wear irregularly - and irregular wear generates noise - and the worse the alignment, the worse the irregular wear. Most of the time, the alignment is good enough that the irregular wear is hardly noticeable, but sometimes it can appear quite quickly. That's why it is important to rotate tires regularly.

4) Small tread elements generate high pitched noise and large tread elements generate low pitched noises. What you want is a mixture. Put another way, even a tread pattern with a lot of elements, but of varying sizes, might not generate as much noise as a tread pattern with fewer, but the same sized, tread elements.
 
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10,142
Location
Jupiter, Florida
Tires can howl when tread blocks wear unevenly from front to back. The leading edge of the tread block wears first, generally caused by braking. In this case, it can be mitigated by rotating tires side to side.
 
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3,066
Location
Western S.C.
... Put another way, even a tread pattern with a lot of elements, but of varying sizes, might not generate as much noise as a tread pattern with fewer, but the same sized, tread elements.
Or as much as a tread pattern with an equal number of same sized elements?

Purposely irregular spacing of tread elements around the circumference to minimize perceived noise has been around for at least 30 years, I believe.
 
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572
Location
Ohio
Tires can howl when tread blocks wear unevenly from front to back. The leading edge of the tread block wears first, generally caused by braking. In this case, it can be mitigated by rotating tires side to side.
The trailing edge of the tread block actually wears faster but the result is still the same - more noise. The cross-rotation (so that the tire is rotating in the opposite direction) will help to even out the "heal-toe" wear. This is a big negative of directional tread patterns. They are designed to always rotate in the same direction so you can never really mitigate the heal-toe wear so the worn directional patterns can become noisy with age.
 
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Messages
10,142
Location
Jupiter, Florida
The trailing edge of the tread block actually wears faster but the result is still the same

It does depend to some extent on braking action. If you rub your hand over the top of a worn tire, you will find that the trailing edge of a tread block is generally worn more. That would be the forward edge of the tread block on the bottom of the tire. Here is an example of a tire that will make noise. On the road, the lower, more worn section of the tread block will be forward, generally more pronounced on the front tires.

 
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