VW Golf manuals

Volkswagen Golf Service & Repair Manual: General notes on tyre noise

Tyre noise that can be heard by the human ear is caused by vibrations which are transmitted by the air from the source of the sound to our ears.
Of interest here are the noises caused by certain characteristics and effects while the tyres are rolling (source of the sound).
The cause of the noise is largely dependent on the combination of the road surface and tyres.
The structure and material of the road surface will greatly affect tyre noise. For example, the noise level on a wet road is much higher than on a dry road.
The pattern of the tyre tread also has a significant influence on tyre noise. Tyres with transverse grooves at an angle of 90° generate more noise than tyres with grooves running diagonally.
Small tread blocks are unstable. Their highly pronounced deformation agitates the air as the tyres roll. This creates the air vibrations that cause tyre noise.
Wider tyres are louder. They need more tread channels to displace water. When they are rolling, these tread channels displace the air, also creating air vibrations.
Further effects that also influence tyre noise:
“Tyre vibration” is the principal cause of tyre noise. It is caused by the columns of air in the tread channels being agitated.
“Air pumping” is the compression and expansion of the air caused by the deformation of the tread blocks as the tyre contact patch moves along the road surface.
Useful information regarding tyre noise
Tyre noise is determined primarily by the tyres and the road surface.
The roughness, structure and material of the road surface influence tyre noise.
The widths of the tyre and the rim, among other things, influence tyre noise. Due to their larger contact area, wider tyres will cause more tyre noise than narrow tyres, as more air has to be displaced and more “mass” is agitated to create vibrations.
A wider wheel rim will also cause a tyre to have a wider contact patch. The effect on tyre noise is thus very similar to that of a wider tyre. Moreover, the damping characteristics of the tyre may also be adversely affected by the wider wheel rim.
On vehicles with a front-mounted engine, tyre noise is more perceptible at the rear of the vehicle, as wind and engine noises are not as loud there.
   
Rolling noise
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Flat spots (from locking wheels)
Flat spots can result from an extreme brake application which causes the wheels to lock, so that the rubber is worn off at the contact patch between the tread and the ...

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