2009 AUDI S4 CABRIOLET suspension

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& WARNING (continued )
• Always make sure that the side airbag can inflate without inter­
ference :
- Never install seat covers or replacement upholstery over the
front seatbacks that have not been specifically approved by
Audi.
- Never use additional seat cushions that cover the areas
where the side airbags inflate.
- Damage to the original seat covers or to the seam in the area
of the side airbag module must always be repaired immedi ­
ately by an authorized Audi dealer.
• The airbag system can be activated only once. After an airbag
has inflated, it must be replaced by an authorized Audi dealer or
qualified technician who has the technical information , training
and special equipment nece ssary.
• The airbag system can be deployed only once . After an airbag
has been deployed , it must be replaced with new replacement
part s designed and approved especially for your Audi model
version. Replacement of complete a irbag systems or airbag
components must be performed by qualified workshops only .
Make sure that any airbag service action is entered in your Audi
Warranty
& Maintenance booklet under AIRBAG REPLACEMENT
RECORD .
• In accidents when an airbag is deployed , the vehicle battery
s eparates the alternator and the starter from the vehicle electrical
system for safety reasons with a pyrotechnic circuit interrupter.
-Work on the pyrotechnic circuit interrupter must only be
performed by a qualified dealer -risk of an accident !
- If the vehi cle or the circuit interrupter is scrapped , all appli ­
cable safety precautions must be followed . •
Controls and equip­ ment Safety first
Vehicle operation
Other things that can affect Advanced Airbag
performance
Changing the vehicle 's suspension system can cha nge the way that
the Advanc ed Ai rbag Syste m perfor ms in a cras h. Fo r ex amp le,
u sing tire -rim combinations not a pproved by Audi, lowering the
ve hicle , c hang ing the st iffness o f the suspe nsion, inclu din g the
spr ings, s uspension struts, shock absorbers etc. can change the
fo rc es that ar e meas ured by th e a irbag sens ors and sent to the e lec ­
tronic control un it. Some suspens ion changes can, for example,
in crea se th e fo rc e leve ls meas ured by th e se nsors and ma ke t he
airbag system dep loy in crash es in wh ich it wou ld not dep loy if the
c h anges had no t been m ade . Ot her k in ds of cha nge s m ay red uce
the fo rce levels measured by the sensors and p revent t he airba g
fr om depl oyin g whe n it should.
T he sensors in the safe ty b elt b uckle fo r the driver a nd front
passenger seat te ll the electronic control module if the safety belt is
l a tc h e d or not. If the s afe ty be lt is bei ng use d, t he fr ont ai rbag w ill
dep loy at a s lightly higher rate of vehic le dece leration than if the
sa fe ty belt is not be ing used . T here for e, in a partic ular co lli sion , it is
possible t hat an airbag will not dep loy at a seating position w here
the safe ty belt is b ein g us ed b ut will infl ate a t th e po siti on w here the
safety belt is not being used. It is important that nothi ng interfere
with the safety belt b uck les so that the sensors can send the correct
i nformat ion about safety b elt use to the electronic control un it.
& WARNING
Changing the vehicle's suspension including use of unapproved
tire -rim combinations can change Advanced Airbag performance
and increase the risk of serious personal injury in a crash.
• Never install suspension components that do not have the
same performance characteristics as the components originally
installed on your vehicle .
• Never use tire-r im combinations that have not been approved
by Audi. .,.
Vehicle care Do-it-yourself service Technical data

___ T_ i_ r_e _s_ a_ n_ d_ vv_ h_ e_ e _ ls _________________________________________________ _
Tire service life
The service life of tires depends on a lot of different things
including proper installation and balancing, correct tire
pressure and driving style .
(r------,')
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Tread Wear Indicator ( TWll
ij
:c ., m
Fig. 209 Tire tre ad:
t read wear ind ica to rs
(TW IJ
Fig . 2 10 Rot ati ng tire s
for mo re even w ear
The orig inal tires on your vehic le have 1 /16 inch (1.6 mm) high "wear
indicators "~ fig. 209 running across the tread . Depending on the
make , there will be six to eight of them evenly p laced around the
tire . Marks on the tire sidewall (for example "TWI" or other symbo ls)
indicate the positions of the tread wear indicators . Worn tires must
be replaced. Dif ferent figures may apply in other countries~&.
Tire pre ssure
Incorrect tire pressure causes premature wear and can cause
sudden tire blow-out . For this reason , tire pressure mus t be checked
at least once a month~
page 274.
Driving style
Driving fast around curves, heavy acce leration and hard braking
increase tire wear .
Rotating t ires for more even wear
For all four tires on your vehicle to have the same service life, we
recommend that the front and rear tires are rota ted according to the
tire manufacturer's suggested tire rotation interva ls . Please
remember the following:
• Tire rotation interva ls may differ from the vehicle service inter­
vals out lined in your Warran ty
& M aintenance Booklet .
• The longer one tire is used in one locat ion on the vehicle, the
more it wears at certain po ints; therefore, we recommend that you
follow the tire manufacturer 's suggested t ire rotation intervals .
• Vehicles with front -wheel drive experience more tread wear on
the front wheels compared to al l-wheel drive (quattro®) .
• Please rotate tires as shown ~
page 278, fig. 210 .
• Extra care must b e taken wh en rotat ing dir ection -specific tires
~ page 298.
Wheel balan cing
The wheels on new vehicles are balanced. However, various situa­
tions during everyday dr iving can cause them to b ecome unbal ­
anced, resulti ng in vibra tions you can usually feel through the
ste ering whee l.
Unbalanced wheels must be rebalanced to avoid excessive wear on
steering , suspension and tires . A wheel must also be reba lanced
when a new tire is installed.
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