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:
Increasing Temperature Due To Low Tire Pressure
The diagram shows the temperature behavior of a tire at
speed of 180 km/h (111.84 mph).
A -
Normal range: when maintaining the specified tire pressure,
the temperature remains stable.
B -
...
Retrofitting a towing bracket
Fig. 92 Dimensions and attachment points
for retrofitting a towing bracket
First read and observe the introductory information
and safety warnings
Volkswagen recommends having the towing bracket retrofitted by a qualified workshop.
The cooling system may need to be modified or heat shields ...
Waxing and polishing the vehicle
First read and observe the introductory information
and safety warningsWaxing
Waxing protects the paintwork. You will need to re-wax the vehicle with a good
hard wax if water no longer clearly forms small drops
and runs off the paintwork when it is clean.
Even if a wax solution is used regul ...
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