Audi A7 Sportback 2015 Owner's Manual page 271

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Wheel bolts
Wheel bolts must always be tightened to the
correct torque .
The design of wheel bolts is matched to the
factory installed rims. If differen t rims are fit-
ted, the correct wheel bolts with the right
length and correctly shaped bolt heads must
be used. This ensures that wheels are fitted
securely and t hat the brake system functions
correctly .
In certain circumstances, you may not use
wheel bo lts from a different vehicle - eve n if it
is the same model ~ page 296.
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WARNING
Improperly tig htened or maintained whee l
bolts can become loose causing loss of
contro l, a collision and serious persona l in-
jury.
- Always keep the wheel bolts and the
threads in the wheel hubs clean so the
whee l bolts can turn easily and be prop-
erly t ightened.
- Never grease or oil the wheel bo lts and
the threads in the wheel hubs. They can
become loose wh ile driving if greased or
oiled, even if tightened to the specif ied
torque .
- Only use wheel bolts that belong to the
rim being installed.
- Never use different whee ls bolts on your
vehicle .
-Always maintain the correct tighten ing
torque for the wheel bo lts to reduce the
risk of a wheel loss . If the tightening tor -
que of the wheel bolts is too low, they
can loosen and come out when the vehi-
cle is moving. If the tightening torque is
too high, the whee l bolts and threads
can be damaged and the wheel can be-
come loose.
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Note
The spec ified torque fo r the wheel bo lts is
90 ft lb (120 Nm) w ith a toleran ce of± 7,4
ft lb(± 10 Nm). Torque wheel bo lts diago-
Tire s an d wheel s 269
nally . After changing a whee l, the torq ue
must be checked as soon as possible with a
torque wrench - preferably by an author-
ized Audi dealer or qualif ied workshop.
Low aspect ratio tires
Your Audi is factory-equ ipped with low aspect
ratio tires . These tires have been thoroughly
tested and been selected specifically for your
model for their superb perfo rmance, road fee l
and hand ling under a variety of driving condi-
tions . Ask your au t horized Audi dealer for
more details .
The low aspect ratio of these t ires is ind icated
by a numera l of
55 or less
in the tire's size
designation. The numera l represents the rat io
of the ti re's sidewall height in relation to its
tread width expressed in percentage . Conven-
tiona l tires have a height/width ratio of 60 or
more.
The perform ance of low-a spect-r atio tire s is
particul arly sensit ive to imp roper infl ation
pressur e . It is t herefore important t hat low
aspect ratio t ires are inflat ed to the specified
pressure and that the inflation pressure is
regularly checked and ma intained. Tire pres-
sures should be checked at least once a
month and always befor e a long trip
~ page 252 , Checking tire pressure.
What you ca n do to avo id tire and rim
damage
Low aspect ratio tires can be damaged more
easily by impact wit h potholes, curbs, gull ies
o r ridges on the road, pa rtic ularly if the tire is
under infla t ed .
In order to minimize the occurrence of impact
damage to the tires of your vehicle, we recom-
mend that you observe the following preca u-
tions:
- Always ma inta in recommended inflation
p ressures . Check your tire pressu re eve ry
2 ,000 miles (3,000 km) and add air if neces-
sary .
- Drive caref ully on roads wit h potholes , deep
gullies o r ridges. The impact from driv ing ..,.
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