wheel AUDI S4 2018 Repair Manual

a co .... N ,....
N .... 0 0
3 co
Airbag System for the front passenger seat from
doing its job in a crash.
The f ront Ad vanced Airb ag S ystem con sists
of t he follo wing :
-Crash sensors in the front of the vehicle that
measure vehicle acceleration/deceleration to
provide information to the Advanced Airbag
System about the severity of the crash.
-An electronic control un it, with integrated
crash sensors for front and side impacts. The
control unit "decides" whether to fire the front
airbags based on the information received from
the crash sensors. The control unit also
"de­
c ides" whether the safety belt pretens ioners
shou ld be activated .
-An Advanced Airbag with gas generator and
contro l valve for the driver ins ide the steer ing
wheel hub.
-An Advanced Airbag with gas generator and contro l valve inside the instrument pane l for
the front passenger.
-A capac itive passenger detect io n system unde r­
neath the front passenger seat cover. This sys­
tem measures the elect rical capac ita nce of the
person in the seat. The i nformation registe red
is sent continuously to the electron ic control
unit to regulate deployment of the front Ad­
vanced Airbag on the passenger side.
-An airbag monitoring system and indicator
light
m in the instrument cluster .
-A sensor in each front seat reg isters 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 control unit to regulate deployment
of the front Advanced A irbags.
-The PA SS EN GER AIR BAG OFF ~; ON@ light
comes on in the
headliner¢ page 283,
fig. 241 and tells you the status of the Ad­
vanced Airbag on the passenge r side .
-A sensor in the safety belt latch for the dr iver
and for the front seat passenger that senses
whether that safety belt is latched or not and
transm its this info rmat ion to the elect ronic
contro l unit.
Airb ag sys tem
_& WARNING
Damage to the front passenger seat can pre­
vent the front airbag from working properly.
- Improper repair or disassembly of the front
passenger and driver seat will prevent the
Advanced Airbag System from funct ion ing
properly.
- Repairs to the front passenger seat must be
performed by qualified and properly trained
workshop personnel.
- Never remove the front passenger or driver seat from the vehicle.
- Never remove the upholstery from the front
passenger seat.
- Never disassemble or remove parts from the
seat or disconnect w ires from it.
- Never carry sharp objects in your pockets or
put them on the seat. The capacit ive pas­
senger detect ion mat in the front passenger
seat will not function p roperly if it is punc­
tured.
- Never carry things on your lap or carry ob­
jects on the front passenger seat. S uch ob­
jects can influence the capacitance reg is­
tered by the capacitive passenger detection
system, so that incorrect informa tion is pro­
vided to the airbag control unit.
- Never store i tems unde r the front passenger
seat . Parts of the Advanced Airbag System
under the passenger seat could be dam­
aged, p reventing them and the airbag sys­
tem from working proper ly.
- Never p lace seat covers or replacement up­
holstery that have not been specifically ap­
proved by Audi on the front seats.
- Seat covers can prevent the Advanced A ir­
bag System from recognizing chi ld re­
stra ints or occupants on the front passenger
seat and prevent the side airbag in the seat
backrest from deploying properly.
- If a seat heater has been retrofitted or oth­
erwise added to the front passenger seat,
never install any child restra int system on
this seat.
- Never use cushions, p illows, blankets, or
similar items on the front passenge r seat .
279

Airbag system
airbag inflates -even with an Advanced Airbag
System.
- 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, door or roof .
- Always install rear-facing child safety seats
on the rear seat .
- If you must install a rearward-facing child
safety seat on the front passenger seat be­
cause of exceptional circumstances and the
PASSENGER AIR BAG OFF~; light does not
come on and stay on, immediately install
the rear-facing child safety seat in a rear
seating position and have the airbag system inspected by your authorized Audi dealer.
A WARNING
Objects between you and the airbag will in­
crease the risk of injury in a crash by interfer­
ing with the way the airbag unfolds or by be­
ing pushed into you as the airbag inflates.
- Never hold things in your hands or on your
lap when the vehicle is in use.
- Never transport items on or in the area of
the front passenger seat. Objects could move into the area of the front airbags dur­
ing braking or other sudden maneuvers and
become dangerous projectiles that can
cause serious personal injury if the airbags
inflate .
- Never place or attach accessories or other
objects (such as cupholders, telephone
brackets, large, heavy or bulky objects) on
the doors, over or near the area marked "AIRBAG'' on the steering wheel, instru­
ment panel, seat backrests or between
those areas and yourself. These objects could cause injury in a crash, especially
when the airbags inflate.
- Never recline the front passenger's seat to
transport objects. Items can also move into
the area of the side airbag or the front air­ bag during braking or in a sudden maneu­
ver. Objects near the airbags can become
282
-
projectiles and cause injury, particularly
when the seat is reclined .
- Never place or transport objects on the
front passenger seat. Objects on the front passenger seat could cause the capacitive
sensor in the seat to signal to airbag system
that the seat is occupied by a person when it
in fact is not, or that the person on the seat
is heavier than he or she actually is. The
change in electric capacitance because of
such objects can cause the passenger front
airbag to be turned on when it should be
off, or can cause the airbag to work in a way
that is different from the way it would have
worked without objects on the seat.
- Always make sure that there is nothing on
the front passenger seat that will cause the
capacitive passenger detection system in
the seat to signal to the Airbag System that
the seat is occupied by a person when it is not , or to signal that it is occupied by some­
one who is heavier than the person actually
sitting on the seat. The presence of an ob­
ject could cause the passenger front airbag
to be turned on when it should be off, or
could cause the airbag to work in a way that
is different from the way it would have
worked without the object on the seat.
A WARNING
The 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 with asthma or other respiratory con­ ditions should get fresh air right away by
getting out of the vehicle or opening win­
dows or doors.
- If you are in a collision in which airbags de­
ploy, wash your hands and face with mild
soap and water before eating.
- 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 .

Airbag syste m
Make sure that the PASSENGER AIR BAG
OFF
11;; li ght comes on and stays on all t he
t ime whenever the ignition is switched on.
A WARNING
- If the PA SSEN GER AIR BAG OFF 11;; light
does not go ou t when an adult is sitting on
the front passe nger seat a fte r ta king the
steps described above, make sure the adult is p roperly seated and restrained at one of
the rear seating positions.
- Have the airbag system inspected by your
authorized Aud i dealer before transporting
anyone on the front passenger seat.
@ Tips
If the capacitive passenger detection system
determines that the front passenger seat is
empty, the frontal airbag on the passenge r
side w ill be tu rned off, and the
PASSENGER
AIR BAG OFF
11;; light will stay on.
-
Repair , care and disposal of the airbags
Parts of the a irbag system are installed at many
different places on your Audi. Installing, remov­ ing, servic ing or repa iring a part in an area of the
ve hicle can damage a part of an airbag system
and prevent that system from working properly
i n a collision .
There are some important things you have to
know to make sure that the effectiveness of the
system w ill not be impaired and that discarded
components do not cause injury or pollute the
env ironment.
A WARNING
Improper care, serv icing and repai r proce­
dures can increase the r is k of personal injury
and death by preventing an airbag from de­
ploying when needed or dep loying an airbag
unexpectedly:
-
- Never cover, obstruct, or change the steer ­
ing wheel horn pad or airbag cover or the in­
strument pane l or modify them in any way.
286
- Never attach any objects s uch as c upholders
or telephone mountings to the surfaces cov­
ering the a irbag un its.
- For cleaning the horn pad or instrument
panel, use only a soft, dry cloth or one mois­
tened w ith plain water. Solvents or cleaners
could damage the airbag cover or change
the st iffness or strength of the material so
that the airbag cannot deploy and p rotect
properly.
- Never repair, adjust, or change any parts of
the airbag system.
- All work on the steering wheel, inst rument
panel, front seats or e lectr ica l system ( in­
cluding the installation of a udio eq uipment,
cellular telephones and C B radio s, etc.)
m ust be perfo rmed by a qualified techn ician
who has the training and specia l equipment
necessary.
- For any work on the airbag system, we strong ly recommend that you see your au­
thorized A udi dealer or qualified workshop.
- Never modify the front b umper or parts of
the vehicle body.
- Always make sure that the side a irbag can
inflate w ithout interference:
- Never install seat covers or replacement
u pholstery ove r the front seatbacks that
have not been specifically approved by
A udi.
- Never use additional seat cushions that
cover the areas where the side airbags in­
flate.
- Damage to the orig inal seat cove rs or to
the seam in the area of the s ide airbag
module mus t always be repaired immedi­
ate ly by an authori zed Au di dealer.
- The a irbag system can deploy on ly once. Af­
ter an airbag h as been deployed, i t m ust be
repla ced with new replacement parts de­
signed and approved espec ia lly for your
Audi model version . Replacement of com­
plete airbag systems or airbag components
must be perfo rmed by qua lified workshops
only. Make sure that any airbag service ac­
tion is entered in your A udi Warranty
&
Ma intenance boo klet under AIRBAG RE-
PLAC EM EN T RECORD.
~

All of this takes place in the blink of an eye, so
fast that many people don't even realize that the 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 .
Fully 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 r isk 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 be lts and airbags
to provide s upplemental protection .
,& WARNING
An inflating knee airbag can cause ser ious in­
jury. Wearing safety bel ts incor rectly and im­
proper seating posit ions increase the r isk o f
serious personal injury and death whenever a
vehicle is being used.
- The knee airbag system cannot protect you
prope rly if you are seated too close to any of
the a irbag locat ions. When ad justing their
seat positions, it is important that both the
dr iver and the front passenger keep their
upper bod ies a nd knees at the following
min imum safe d istances:
- at least 10 inches (25 cm) between the
chest and the steering wheel/instrument
panel.
- at least 4 inc hes (10 cm) between the
knees and the lower part of the instru­
ment panel.
- The risk of persona l injury increases if you
lean forward or to the side, or if the seat is
improper ly positioned and you are not wear­
ing your safety belt. The risk increases even
more should the a irbag deploy.
- Always make sure that the knee airbag can
inflate without interference. Objects
be-
Airb ag sys tem
tween you and the airbag can increase the
risk of injury in an accident by interfering
wit h the way the airbag deploys or by being
pushed into yo u as the a irbag deploys.
- Never let anybo dy, especi ally children or
anima ls r ide in the footwell i n front of the
passenger seat. If the airbag deploys, this
can result in serious o r fatal in juries.
- Never carry objects of any kind in the foo t­
well area in front of the driver's or pas­
senger's seat . Bulky objects (shopp ing
bags, for example) can interfere with or
prevent proper dep loyment of the airbag.
Small objects can be thrown th rough t he
vehicle if the airbag deploys and injure you
o r your passengers.
- Make sure the re a re no cracks, deep scratch­
es o r othe r damage in the area of the inst ru­
ment panel where the knee airbags a re lo­
ca ted.
- If ch ildren are incorrectly seated, their risk
of injury inc reases in a coll is ion
~ page 29 5, Child safe ty.
Side airbags
Description of side airbags
The airbag system can provide supplemental
protection to properly restrained occupants.
Fi g. 2 44 Side a irbag locat ion in the drive r's sea t
The side airbags are located in the s ides of the
front seat
backrests ~ fig. 244 and the rear back­
res t* facing the doo rs.
The side airbags installed for the front seating
pos itions have been des igned and certified to
help reduce the risk of in ju ry that can be caused
by a irbags when they inflate, pa rticul arly when
.,.
289

Wheels
Wheels
Whee ls and Ti res
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 N ote
-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
33 4
and b raking 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
F ig. 27 4 Tire des ignat ions on the side-
wall II>

a co .... N ,....
N .... 0 0
3 co
(D Tires for passenger vehicles
(if applicable)
"P" indicate s a tir e for a p ass enger
vehi cle . "T" indicates a tire de sig­
nated for temporary us e.
@ 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
Siz e of the rim diameter in inches.
@ Load index and speed rating
The load ind ex indi cates the tire' s
lo ad-ca rry in g ca pacity.
The speed rating indicates the maximum permitted
speed ¢.& in
W inter tires o n page 349 .
"EXTRA LOAD", "xl" or "RF" indi­
cate s that the tire i s reinfor ced or
is an Extra Load tire.
Speed rat- Maximum permitted speed
ing
p
up t o 93 mph ( 150 km/h)
Q up to 99 mph (160 km/ h)
Wheels
Speed rat- Maximum permitted speed
ing
R up to 106 mph (170 km/h)
s u p to 11 0 mph ( 180 km/h)
T up to 118 mph (190 km/h)
u u p to 124 mph ( 200 km/h)
H up to 130 mph (210 km/h)
V up to 14 9 mph (2 40 km/h) al
z above 149 mph (240 km/h)al
w u p to 168 mph (270 km/h) al
y up to 1 86 mph (300 km/h)al
a) Fo r tir es ab ove 149 mph (2 40 km/h),
t ir e man ufact ure rs sometimes use the
co de
"Z R".
(j) US DOT number (TIN) and
manufacture date
The m anufac ture date i s listed on
the tire sidewall (it ma y only ap­
pear on the inner side of the tire):
DOT ... 2216 ...
means, for example , that the tire
was produced in the 22nd week of
the year 2016.
@ Audi Original Tires
Audi Original equipment tire s
with the de signation "AO" ha ve
been specially matched to your
Audi. When used correctl y, these
tires meet the high est standards
for safety and handling. An au­
thorized Audi dealer o r author­
ized Audi Ser vice Fa cilit y will be
a ble to pr ovide you with more in-
formation .
""
335

Wheel s
® Mud and snow capability
"M/5" or "M+S" indicates the tire
is sui table for driving on mud and
snow.
& indicates a winter tire.
@ Composition of the tire cord
and materials
The number of plies indicates the
number of rubberized fabric lay­
ers in the t ire. In general: the
more layers, the more weight a
tire can carry . Tire manufacturers
must also specify the materials
used in the tire. These include
steel, nylon, po lyester and other
materials.
@ Maximum permitted load
This number indicates the maxi­
mum load in kilograms and
pounds that the tire can carry .
@Uniform tire quality grade
standards for treadwear,
traction and temperature resist ance
Treadwear, traction and tempera­
ture
ranges ¢ page 351.
@ Running direction
The arrows indicate the running
direction of unidirectional t ires .
You must always follow the speci­
fied running direction
¢page 366 .
336
@ Maximum permitted
inflation pressure
This number indicates the maxi­
mum pressure to which a tire can
be inflated under normal operat ­
ing condit ions.
Glossary of tire and loading
terminology
Acces sory we ight
means the combined weight (in
excess of those standard items
which may be replaced) of auto­ matic transmission, power steer­
ing, power brakes, power win­
dows, power seats, radio, and
heater, to the extent that these
items are available as factory-in­
stalled equipment (whether in ­
stalled or not) .
Aspect ratio
means the ratio of the height to
the width of the tire in percent .
Numbers of 55 or lower indicate a
low sidewall for improved steer­
ing response and better overall
handling on dry pavement.
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 r im .
...

0 C0 .-< N ..... N .-< 0
~ a:,
Bead separa tion
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 standard equipment in­
c luding the maximum capac ity of
fuel, oi l, and coolant, a ir condi­
tioning and add itional weight of
optional equipment.
E xtra load tire
means a tire designed to operate
at higher loads and at h igher in ­
flation pressures than the corre­ sponding standard tire. Extra load
tires may be identified as
"X L",
"xl", "E XTRA LOAD" , or "RF" on
the s idewal l.
Wheels
Gross Axle Weight Rating
( " GAWR")
means the load-carrying capacity
of a single axle system, measured
at the tire -ground interfaces.
Gross Vehicle Weight Rating
(" GVWR ")
means the max imum total loaded
weight of the vehicle.
Groove
means the space between two ad­
jacent tread ribs .
Load rating (code)
means the maxim um load that a
tire is rated to carry for a given in­
flat ion pressure . You may not f ind
this informat ion on all tires 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 the sum of:
(a) Curb weight
(b) Accessory weight
(c) Vehicle capacity we ight , and
(d) Production options we ight
33 7

Wheel s
Maximum (permissible)
inflation pressure
means the max imum cold infla­
tion pressure to which a t ire may
be inflated . Also called "maxi ­
mum inflation pressure."
Normal occupant weight
means 150 lbs. (68 k ilograms)
times the number of occupants seated in the vehicle up to the to­
tal seating capacity of your vehi­
cle .
Occupant distribution
means distribution of occupants
in a vehicle.
Outer d iameter
means the overall diamete r 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 .
Ply
means a layer of rubber-coated
para llel cords.
338
Production options we ight
means the combined weight of
those installed regular product ion
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 ti re
means a pneumatic tire in which
the ply cords that extend to the beads are la id at substantially 90
degrees to the centerline of the
tread.
Recommended inflation
pressure
see ¢ page 33 7, Cold tire infla­
tion pressure.
Reinforced tire
means a tire designed to operate
at higher loads and at higher in­
flation pressures than the corre­
sponding standard tire . Rein ­
forced tires may be identified as
"XL", "xl", "EXTRA LOAD", or "RF"
on the sidewall. ...

0 C0 .-< N ..... N .-< 0
~ a:,
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 t ire is
designed to be driven for extend­
ed periods of time . The ratings
range f rom 93 mph (150 km/h)
to 186 mph (298 km/h)
¢ table
on page 335.
You may not find
this information on all tires be­
cause it is not required by law.
The speed rating letter code ,
w here applicable, is molded o n
the tire sidewall and indicates the
Wheels
maximum permissible roa d
speeds
¢ A in Winter tires on
page 349.
Tire pressure monitoring
system
means a system that detects
when one or more of a vehicle's
ti res are underinflated and illumi­
na tes a low tire pressure warning
telltale.
Tread
means that po rtion of a ti re that
comes i nto contact with the road .
Tread separation
means pulling away of the tread
from the tire carcass.
Treadwear indicators (TWI)
means the projections withi n the
principa l grooves desig ned to g ive
a visua l indication of the degrees
of wear of the t read. See
¢ page 343, Treadwear indicator
for mo re in fo rmat ion on meas ur­
ing t ire wear .
Uniform Tire Quality Grading
is a tire information system devel­
oped by the United Sta tes Nation­
a l Highway Traffic Safety Admin­
istration ( NHTSA) tha t is designed
to help buyers make re lat ive
339
..