Volkswagen Polo Service & Repair Manual: Tires, Rolling Noises, General Information
| Rolling noise perceived by the human ear is caused by
vibrations transmitted from the noise source to the ear via the
air. |
| Here we are interested in noises created by certain
characteristics of the tires as well as the effects of rolling
(noise source). |
| The cause for the noise generation depends primarily on the
combination of road surface and tire. |
| The surface structure and material of the road surface also
have a strong influence on the rolling noise. For example, the
noise level on a wet road is substantially higher than on a dry
road. |
| The design of the tread has a great influence on the noise
generation. Tires with cross grooves at an angle of 90° are
louder than tires with grooves running diagonally. |
| Small tread blocks are unstable. Due to strong deformation,
the air is excited by the rolling tires. Air vibrations occur,
which will generate noises. |
| Wider tires are louder. They require more tread grooves for
water displacement. Air is displaced by these tread grooves
while rolling, which also cause air vibrations. |
| Other effects which also have an influence on noise
generation: |
| “Tire vibration” is the main cause of rolling noise. The
noise is generated by the excitation of the air column in the
grooves. |
| “Air pumping” is the compression and expansion of air as the
contact patch comes in contact with the road surface and the
tread blocks are deformed. |
| Aid to Reasoning of Rolling Noise |
| Noise generation is created chiefly by tires and the road
surface. |
| Influencing factors of road surface are roughness, structure
and material. |
| Influencing factors for tires fall under different tire and
rim widths. A wider tire generates more noise due to its wider
contact patch than a narrower tire does, because more air is
displaced and a greater “mass” is caused to vibrate. |
| A wider rim also causes the tire to have a wider contact
patch. The effects on noise generation are basically the same as
those of a wider tire. In addition, the noise suppression
characteristics of the tire can, under certain circumstances, be
negatively affected by the wider rim. |
| The tire rolling noise is significantly noticeable in the
rear of vehicles with front engines, because wind and engine
noise are less audible in the back. |
|
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Wear spots are caused by a hard stop with locked wheels
whereby the rubber compound is abraded from the contact patch.
When the tires slide across th ...
Other materials:
Flushing Circuit Block Diagrams
Note
The arrows in the following illustrations show the direction
of refrigerant flow while flushing. During flushing, refrigerant
flows in the opposite direction than during A/C system
operation, therefore the high pressure side of A/C se ...
General Information
WARNING
Risk of injury.
Read and follow the Safety Precautions when working
with batteries. Refer to
→ Chapter „Warnings and Safety Precautions“.
...
General Information
Tongue Weight Specifications
The tongue weight specifications on the trailer hitch type
label are inspection values and only valid for the hitch. The
permitted tongue weight for the vehicle may be less and it must
not b ...
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