wheel AUDI A8 2018 Workshop Manual

Airbag syste m
passenger seat contains important parts of the
Advanced Airbag System, you must take care to
prevent it from being damaged . Damage to the
seat may prevent the Advanced A irbag for the
front passenger seat from doing its job in a
crash .
The front Ad vanced Airb ag S ystem con sist s
o f the follo wing :
-Crash sensors in the front of the vehicle that
measure vehicle acceleration/decelerat ion to
provide information to the Advanced Airbag
System about the severity of the crash .
- An electron ic control un it, with integrated
crash sensors for front and side impacts . The
contro l unit "decides " whether to fire the front
airbags based on the information received from
the crash sensors. The contro l unit also "de ­
cides" whether the safety be lt pretensioners
sho uld be activated.
-An Advanced Airbag with gas generator and
contro l valve for the driver inside the steering
whee l hub .
-An Advanced Airbag with gas generator and
contro l valve inside the instrument pane l for
the front passenger.
- A weight -sensing mat unde r th e upho lstery
padding of the front passenger seat cushion
that meas ures the tota l weight on the seat . T he
information registered is sent continuously to
the e lec tronic control unit to regu la te dep loy­
ment of the front Adva need A irbag on the pas ­
senger side .
- An airbag monitoring system and indicator
light in the instrument cluster
c> page 23 7 .
- A sensor in each front sea t registers the dis­
tance between the respective seat and the
steering wheel or instrument panel. The infor­
mation reg istered is sent continuously to the
electronic cont rol u nit to regulate deployment
of the fro nt Advanced A irbags.
- T he
PASSENGER AIR BAG OFF light comes on
and stays on in the center of the instr ument
pane l
c> page 23 7, fig. 232 and tells you w hen
the front Advanced Airbag on the passenger side has been turned off.
-A sensor be low the safety belt latch fo r the
front seat passenger to meas ure the tension on
234
the sa fety be lt. The tension on the safety belt
and the weight registered by the weight -sens­
ing mat he lp the contro l unit "decide" whether
the front airbag for the front passenger seat
should be turned
off or not c> page 228, Child
restraints on the front seat -some important
things to know .
-A sensor in the safety belt latch for the driver
and for the front seat passenger that senses
whether that safety belt is latched or not and
transmits this informat ion to the e lectronic
cont rol u nit.
_&, WARNING
Da mage to the front passenge r seat can pre ­
vent the front airbag from work ing prope rly .
- I mp roper repair or disassembly of the front
passenger and driver seat will p revent the
Advanced Airbag System from functioning
proper ly.
-Repairs to the front passenger seat mus t be
performed by qualified and proper ly trained
workshop personne l.
- Never remove the front passenger or driver seat from the vehicle.
-Never remove the upholstery from the front
passenger seat.
-N ever d is a ssemble o r remove pa rts from the
seat or disconnect wi res from it.
- N ever carry sharp objects in your pocke ts or
p lace them on the seat. If the weight-sens ­
ing mat in the passenger seat is p unctured
it ca nnot work proper ly.
- Never carry things on your lap or carry ob­
jects on the passenger seat. S uch items can
increase t he weight reg istered by the
weight-sensing mat and send the wrong in­ formation to the a irbag control u nit.
- Never store items under the front passenger
seat . Parts of the Advanced Airbag System
under the passenger seat cou ld be dam­
aged, preventing them and the airbag sys­
tem from worki ng p roperly.
- Never place seat covers or replacement up­
holstery that have not been specifically ap­
proved by A ud i on the front seats.
- Seat covers can prevent the Advanced A ir­
bag System from recognizi ng ch ild

the doors, over or near the area marked
"AIRBAG" on the steering wheel, instru­
ment pane l, seat backrests or between
those areas and yourself . These objects
cou ld cause injury in a crash, especially
when the airbags inflate .
-Never recline the front passenge r's seat to
transport objects. Items ca n also move into
the area of the side airbag o r the front air­
bag during bra king or in a sudden maneu­
ver. Objects near the airbags can become
projectiles and cause in jury, particularly
when the seat is reclined.
A WARNING
T he fine dust created when airbags deploy can
cause breathing problems for people with a
history of asthma or other breathing condi­
tions.
-To reduce the risk of breathing problems,
those w ith asthma or other respiratory con­
ditions should get fresh air right away by
gett ing out of the veh icle or opening w in­
dows or doo rs.
-If you are in a collision in which airbags de­
ploy, wash your hands and face with mild
soap and water before eat ing .
-Be careful not to get the dust into your eyes,
or into any cuts or scratches .
-If the residue should get into your eyes,
flush them with water.
Monitoring the
Advanced Airbag System
~ ( USA models )/!{ (Canada models )
Airbag monitoring indicator light
Two separate indicators monitor the function of
the Advanced Airbag System: the airbag moni­
toring indicator light and the
PASSENGER AIR
BAG OFF
light.
The Advanced Airbag System (including the elec­
tron ic control unit, sensor c ircuits and system
~ wir ing) is monitored continuously to make sure
;:::: that it is funct ion ing prope rly whenever the igni-
" ~ tion is on. Each time you switch on the ignition,
~ the airbag monitoring indicator light fl (USA '<I'
Airbag system
models)/EI (Canada models) w ill come on for a
few seconds (se lf diagnostics).
The system must be inspected when the
indicator light
II (USA models)tE,I (Canada
models) :
-does not come on when the ignition is switched
on,
-does not go out a few seconds after you have
sw itched on the ignition, or
-comes on while driving.
If an airbag system malfunction is detec ted, the
indica tor light will come on to serve as a constant
reminder to have the system inspected immedi­
ately .
If a malfu nction occurs that turns the front air­
bag on the passenger side off, the
PASSENGER
AIR BAG OFF
light will come on and stay on
whenever the ignition is on.
A WARNING
An airbag system that is not functioning prop­
erly cannot prov ide supplemental protect ion
i n a fronta l crash.
-If the airbag indicator light ¢ page 23
comes when the veh icle is being used, have
the system inspected immediately by your
author ized Audi dealer.
It is poss ible that
the airbag will inflate when it is not sup­
posed to, or w ill not inf late when it should.
PASSENGER AIR BAG OFF light
Fi g. 232 Sect io n from th e instrument panel: PASSENGER
AIR BAG O FF lig ht
T he PASSENGER AIR BAG OFF light is located in
the center of the instrument
panel ¢ fig. 232. Ill>
237

Airbag syste m
(D Tips
If the weight-sensing mat in the front passen ­
ger seat detects an empty seat, the front air ­
bag on the passenger side w ill be turned off,
and the
PASSEN GER AIR BAG OFF light will
stay on.
Repair, care and disposal of the airbags
Parts of the a irbag system are installed at many
d ifferent p laces on your Aud i. Install ing, remov­
i n g, servic ing o r repa iring a part in an area of the
ve hicle can damage a pa rt of an airbag system
and prevent that system from working properly
in a co llision .
There are some important t hings yo u have to
know to make sure th at the effect iveness of the
system wi ll not be impaired and that dis carded
components do not cause injury or pollute the
environment .
A WARNING
Improper care, serv icing and repair proce­
dures can increase the r isk of personal injury
and death by preventing an airbag from de­
ploying when needed or deploying an airbag
unexpectedly:
-
-Never cover, obstruct, or change the steer­
i ng wheel horn pad or a irbag cover or the in­
strument pa ne l or mod ify them in any way.
-Never attach any objects such as cup holders
o r te lephone mount ings to the surfaces cov­
er ing the ai rbag units.
-For cleaning the horn pad or instrument
pane l, use on ly a soft, dry cloth or one mois­
tened with plain water. Solvents or cleaners cou ld damage the airbag cover or change
the stiffness or st rengt h of the materia l so
t h at the airbag cannot dep loy and protect
properly.
-Never repair, adjust, or change any parts of
the airbag system.
-All work on the stee ring wheel, i nstr ument
pane l, front seats or electrical system (in ­
cluding the installation of audio equipment,
ce llular telephones and CB rad ios, etc.)
must be performed by a qualified technician
240
who has the training and specia l equipment
necessary.
-F or any work on the airbag system, we
strong ly recommend that you see yo ur au­
thorized Audi dealer or qualified workshop.
-Never modify the front b umper or parts of
the vehicle body.
- Always make sure that the side airbag can
inflate w ithout interference:
-Never install seat covers or replaceme nt
upholstery ove r the front seatbacks that
have not bee n specific ally app roved by
A udi.
-Neve r use additional seat c ushi ons that
cover the areas where the side airbags in ­
flate.
-Damage to the orig inal seat cove rs o r to
t h e seam in the area of the s ide airb ag
module mus t always be repai red immedi ­
ate ly by an authorized Audi dealer.
-The airb ag sys tem can be act iv a ted only
once . A fter an airbag has in flated, it must
be replaced by an authorized Audi dealer or
qua lified tech nic ian who has the technical
information, train ing and spec ial equ ipment
necessary.
-The airbag system can be deployed only
once. After an airbag has been deployed, it
must be replaced with new rep lacement
parts des igned and approved espec ially for
your Aud i model version. Replacement of
comp lete airbag systems or airbag compo­
nents must be perfo rmed by qualified work­
shops only. M ake sure that any a irb ag se rv ­
ice act ion is entered in your Audi Warranty
& Maintenance booklet under AIRBAG RE ­
PLACEMENT RECORD.
-For safety reasons in severe accidents, the
a lter nator and starter a re separated from
the vehicle battery with a pyrotechnic circu it
interrupter.
-Wo rk on the pyrotechnic c ircuit inte rrupt­
e r must o nly be perfo rmed by a qua lified
dealer
-r isk of an a cciden t!
-If the vehicle or the c ircuit inte rr u pte r is
sc rapped, all appli cable safety p recau tions
mus t be followed.
..,.

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airbags have deployed. The airbags also inflate
with a great deal of force and it is important for
occupant safety that nothing should be in their
way when they deploy .
Full y inflated airbags in comb ination with proper­
ly worn safety belts slow down and limit the oc­
cupant's forward movement and help to reduce
the risk of injury.
Important safety instructions on the knee
airbag system
Airbags are only supplemental restraints. Always
wear safety belts correctly and ride in a proper
seating position .
There is a lot that you and your passengers must
know and do to help the safety belts and airbags
to provide supplemental protection .
A WARNING
An inflating knee airbag can cause serious in­
jury. Wearing safety belts incorrectly and im­
proper seating positions increase the risk of
serious personal injury and death whenever a
vehicle is being used.
- The knee airbag system cannot protect you
properly if you are seated too close to any of
the airbag locations. When adjusting their
seat positions, it is important that both the
driver and the front passenger keep their
upper bodies and knees at the following
minimum safe distances :
- at least 10 inches (25 cm) between the
chest and the steering wheel/instrument
panel.
- at least 4 inches (10 cm) between the
knees and the lower part of the instru­
ment panel.
- The risk of personal injury increases if you
lean forward or to the side, or if the seat is
improperly positioned and you are not wear­
ing your safety belt. The risk increases even
more should the airbag deploy.
-Always make sure that the knee airbag can inflate without interference. Objects be­
tween you and the airbag can increase the risk of injury in an accident by interfering
Airbag system
with the way the airbag deploys or by being
pushed into you as the airbag deploys.
- Never let anybody, especia lly children or
animals r ide in the footwell in front of the
passenger seat. If the airbag deploys, this
can result in serious or fatal injuries.
- Never carry objects of any kind in the foot­
well area in front of the driver's or pas­
senger's seat . Bulky objects (shopping
bags, for example) can interfere with or
prevent proper deployment of the airbag.
Small objects can be thrown through the
vehicle if the airbag deploys and injure you
or your passengers.
- Make sure there are no cracks, deep scratch­
es or other damage in the area of the instru­
ment panel where the knee airbags are lo­
cated.
- If children are incorrectly seated, their risk
of injury increases in a collision
<=> page 249, Child safety .
Side airbags
Description of side airbags
The airbag system can provide supplemental
protection to properly restrained occupants.
Fig. 235 Side a irbag locatio n in the driver's seat
The side airbags are located in the sides of the
front seat backrests
<=> fig . 235 and the rear back­
r est facing the doors . They are identified by the
word "AIRBAG" .
The side airbag system basically consists of:
-the electronic control module and external side
impact sensors
.,..
243

Child sa fety
A WARNING
Children on the front seat of any car even with
Advanced Airbags can be seriously injured or even killed when an airbag inflates. A child in
a rearward-facing child safety seat installed
on the front passenger seat will be seriously
injured and can be killed if the front airbag in­
flates.
- The inflating airbag will hit the child safety
seat or infant carrier with great force and
will smash the child safety seat and child
against the backrest, center armrest, o r
doo r.
- Always install rear-facing child safety seats
on the rear seat.
- If you must install a rearward fac ing ch ild
safety seat on the front passenger seat in
exceptional c ircumstances and the
PASSEN­
GER AIR BAG OFF
light does not come on
and stay on, immediately insta ll the rear ­
facing child safety seat in a rear seating po­ sition and have the airbag system inspected
immediately by your Audi dealer.
A WARNING
If, in except ional circumstances, you must in­
stall a forward-facing chi ld restraint on the
front passenger's seat:
- Always make sure the forward-facing seat
has been designed and cert ified by its man­
ufacturer for use on a front seat with a pas­
senger front and side a irbag .
- Always follow the manufacturer's instruc­
t ions prov ided with the ch ild safety seat or
earner.
- Always move the front passenger seat to
the h ighest position in the up and down ad­
justment range and move it back to the
rea rmost position in the seat's fore and aft
adjus tment range, as fa r away from the air­
bag as possib le, before insta lling the for­
ward- facing child restraint .
- Always make sure tha t the s afety belt upper
anchorage is beh ind the child restraint and
not next to or in front of the child restraint
so that the safety belt will be properly posi­
tioned.
250
- Always make sure that the PASSENGER AIR
BAG OFF
light comes on and stays on all the
time whenever the ign it ion is switched on.
(D Tips
A lways replace child restraints that were in­
stalled in a vehicle during a c rash . Damage to
a child restraint that is not v is ible could cause
i t to fai l in another co llision situat ion.
Advanced front airbag system and children
Your vehicle is equ ipped with a front "Advanced
A irbag System" in compl iance with U nited States
Federal Motor Veh icle Safety Standard (FMVSS)
208, as we ll as Canada Moto r Vehicle Safety
Standa rd ( CMVSS) 208 as applicab le a t the t ime
you r vehicle was manufactured.
The Adva nced A irbag system in yo ur vehicle has
been certified to mee t the "low- risk" require­
ments fo r
3-and 6 -yea r old chi ld ren on the pas ­
senger side and sma ll adu lts on the driver s ide.
The low risk deployment criteria are intended to
reduce the risk of inj ury t hrough interaction with
the airbag that can occur, for example, by be ing
too close to the steering wheel and instrument panel whe n the airbag inflates. In addition, the
system has been cert ified to comply with the
"supp ression" requirements of the Safety Stand­
a rd, to tur n off the front a irbag for infants up to
12 months who are restrained on t he fro nt pas ­
senger seat in c hild restraints t hat are lis ted in
t h e Standard.
E ven thoug h your veh icle is eq uipped w it h an Ad­
vanced Airbag system, all ch ild ren, especially
t h ose 12 yea rs and younger, sho uld always ride
i n the back seat proper ly restrained for their age
and size. The airbag on the passenger side makes
t h e front seat a potentially dange rous p lace for a
ch ild to ride. The front seat is not the safest place
for a ch ild in a forward-facing ch ild safety seat. It
can be a very dangerous place for an infant or a
larger ch ild in a rearward-facing seat .

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Wheels
Wheels and Tires
General information
~check your tires regularly for
damage (punctures, cuts, cracks
and bulges). Remove foreign ob­
jects from the tire tread.
~ If driving over curbs or similar
obstacles, drive slowly and ap ­
proach the curb at an angle.
~Have faulty tires or rims re­
placed immediately.
~Protect your tires from oil,
grease and fuel.
~Mark tires before removing
them so that the same running
direction can be maintained if
they are reinstalled.
~Lay tires flat when storing and
store them in a cool, dry location
with as little exposure to light as possible.
(D Note
-Please note that summer and winter tires are designed for
the conditions that are typical in those seasons. Audi recom­
mends using winter tires dur­
ing the winter months. Low
temperatures significantly de­
crease the elasticity of summ­
er tires, which affects traction
Wheels
and braking ability. If summer
tires are used in very cold
temperatures, cracks can form on the tread bars, resulting in
permanent tire damage that
can cause loud driving noise
and unbalanced tires.
-Burnished, polished or chromed rims must not be
used in winter driving condi­
tions. The surface of the rims does not have sufficient corro­
sion protection for this and
could be permanently dam­
aged by road salt or similar
substances.
Tire designations
Fig. 264 Tire specification codes on the
sidewall of a tire
.,.
283

Wheels
(D Tires for passenger vehicles
(if applicable)
"P" indicates a tire for a passenger
vehicle. "T" indicates a tire desig­
nated for temporary use.
@ Nominal width
Nominal width of the tire be­
tween the sidewalls in millime­
ters. In general: the larger the number, the wider the tire.
@ Aspect ratio
Height/width ratio expressed as a
percentage.
© Tire construction
R indicates a radial tire.
® Rim diameter
Size of the rim diameter in inches.
@ Load index and speed rating
The load index indicates the tire's
load-carrying capacity.
The speed rating indicates the maximum permitted speed
c> & in
Winter tires on page 298.
"EXTRA LOAD", "xl" or "RF" indi­
cates that the tire is reinforced or
is an Extra Load tire.
Speed rat-
Maximum permitted speed
ing
p
up to 93 mph (150 km/h)
Q up to 99 mph (160 km/h)
284
Speed rat- Maximum permitted speed
ing
R up to 106 mph (170 km/h)
s up to 110 mph (180 km/h)
T up to 1 18 mph (190 km/h)
u up to 124 mph (200 km/h)
H up to 130 mph (210 km/h)
V up to 149 mph (240 km/h) al
z above 149 mph (240 km/h)a)
w up to 168 mph (270 km/h) al
y up to 186 mph (300 km/h)a)
a) For tires above 149 mph (240 km/h),
tire manufacturers sometimes use the
code
"ZR".
0 US DOT number (TIN) and
manufacture date
The manufacture date is listed on
the tire sidewall (it may only ap­
pear on the inner side of the tire):
DOT ... 2217 ...
means, for example, that the tire
was produced in the 22nd week of
the year 2017.
@ Audi Original Tires
Audi Original equipment tires
with the designation "AO" have
been specially matched to your
Audi. When used correctly, these
tires meet the highest standards
for safety and handling. An au­
thorized Audi dealer or author­
ized Audi Service Facility will be
able to provide you with more in­
formation.

Wheels
Bead
means the part of the tire that is
made of steel wires, wrapped or
reinforced by ply cords and that is
shaped to fit the rim .
Bead separation
means a breakdown of the bond
between components in the bead .
Cord
means the strands forming the
plies in the tire .
Cold tire inflation pressure
means the tire pressure recom­
mended by the vehicle manufac­
turer for
a tire of a designated
size that has not been driven for more than a couple of miles (kilo­
meters) at low speeds in the
three hour period before the tire pressure is measured or adjusted .
Curb weight
means the weight of a motor ve­
hicle with standa rd equipment in ­
cluding the maximum ca pacity of
fuel, oil, and coolant, air condi ­
tioning and addit ional weigh t of
optional equipment.
E x tra load tire
means a tire designed to operate
at higher loads and at higher
in -
28 6
flation pressures than t he corre­
spond ing standard tire. Extra load
tires may be identified as "X L",
"xl" , "EXTRA LOAD" , or "RF" on
the sidewall.
Gross Axle Weight Rating ("GAWR")
means the load-car rying capacity
of a single axle system , measu red
at the ti re-ground interfaces .
Gross Vehicle Weight Rating
("GVWR")
means the maximum total loaded
weight of the vehicle .
Groove
means the space between two ad­
jacent tread ribs .
Load rating (code)
means the maximum load tha t a
tire is rated to carry for a given i n­
flation pressure. You may no t find
this informat ion on all ti res be­
cause it is not required by law .
Maximum load rating
means the load rating for a tire at
the maximum permissible infla­
tion pressure for that tire .
Maximum loaded vehicle
weight
means t he sum of:

....
"' -N .... N
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0
J: ..
(a) Curb weight
(b) Accessory weight
(c) Vehicle capacity weight, and
(d) Production options weight
Ma ximum (permissible }
inflation pres sure
means the maximum cold infla­
tion pressure to which a t ire may
be inflated . Also called "maxi ­
mum inflation pressure."
Normal occupant weight
means 150 l bs. (68 kilograms)
times the number of occupants
seated in the veh icle up to the to­
tal seating capacity of your vehi­
c le.
Occupant distribution
means distribution of occupants
in a vehicle.
Outer diameter
means the overall diameter of an
inflated new tire .
Overall width
means the linear distance be­
tween the exteriors of the side­
walls of an inflated tire, including
elevations due to labeling, deco­
rations, or protective bands or
ribs .
Wheels
Ply
means a layer of rubber-coated
parallel cords .
Production options weight
means the combined weight of
those installed regular production
options weighing over 5 lbs. (2.3 kg) in excess of those standard
items which they replace, not pre ­
viously considered in curb weight
or accessory weight, including heavy duty brakes , ride levelers ,
roof rack, heavy duty battery, and
special trim .
Radial ply tire
means a pneumatic tire in which
the ply cords that extend to the beads are laid at substantially 90
degrees to the centerline of the
tread .
Recommended inflation
pressure
see ~ page 286, Cold tire infla­
tion pressure .
Reinforced tire
means a tire designed to operate
at higher loads and at higher in­
flat ion pressures than the corre­
sponding standard tire. Rein ­
forced tires may be iden tified as
.,.
28 7

Wheels
"XL" "xl" "EXTRA LOAD" or "RF" I I I
on the sidewall.
Rim
means a metal support for a tire
or a tire and tube assembly upon
which the tire beads are seated.
Rim diameter
means nominal diameter of the
bead seat . If you change your
wheel size, you will have to pur ­
chase new tires to match the new rim diameter .
Rim size designation
means rim diameter and width .
Rim width
means nominal distance between
rim flanges.
Sidewall
means that portion of a tire be­
tween the tread and bead .
Speed rating (letter code)
means the speed at which a tire is
designed to be driven for extend­
ed periods of time. The ratings range from 93 mph (150 km/h)
to 186 mph (298
km/h)¢ table
on page 284 .
You may not find
this information on all tires be­
cause it is not required by law .
288
The speed rating letter code,
where applicable, is molded on the tire sidewall and indicates the maximum permissible vehicle
speeds
¢ .1,. in Winter tires on
page 298 .
Tire pressure monitoring
system*
means a system that detects
when one or mo re of a vehicle 's
tires are underinflated and illumi­
nates a low tire pressure warning
telltale .
Tread
means that portion of a tire that
comes into contact with the road .
Tread separation
means pulling away of the tread
from the tire carcass .
Treadwear indicators (TWI )
means the projections within the
principal grooves designed to give
a visual indication of the degrees
of wear of the tread. See
¢ page 292, Treadwear indicator
for more information on measur- ing tire wear.
.,.