tires AUDI R8 SPYDER 2011 User Guide

Maximum loaded vehicle weight
means the sum of:
(a) Curb weight
(b) Accessory weight
(c) Vehicle capacity weight, and
(d) Production options weight
Maximum (permissible) inflation pressure
means the maximum cold inflation pressure
to which a tire may be inflated. Also called
"maximum inflation pressu re."
Normal occupant weight
means 150 lbs. (68 k ilograms) times the
nu mber of occupants seated in the vehicle up
to the total seating capacity of your vehicle.
Occupant distribution
means distribution of occupants in a vehicle .
Outer diameter
means the overa ll diameter of an inflated new
tire.
Overall width
means the linear distance between the exteri­
ors of the sidewalls of an inflated tire, includ­
ing e levations due to labeling, decorations, or
protective bands or ribs.
Ply
means a layer of rubber-coated para llel cords.
Production options weight
means the comb ined weight of those installed
regular production options weighing over 5
lbs . (2 .3 kg) in excess of those standard items
which they replace, not previously considered
in curb weight or accessory weight, including
heavy duty brakes, r ide leve lers, roof rack,
heavy duty battery, and specia l trim .
Radial ply tire
means a pneumatic t ire in which the p ly cords
that extend to the beads are laid at substan­
tially 90 degrees to the centerline of the
tread.
Tires and wheels 191
Recommended inflation pressure
see ~ page 190, Cold tire inflation pressure.
Reinforced tire
means a t ire designed to operate at higher
loads and at higher inflat ion pressures than
the corresponding standard tire. Re inforced
ti res my be ident ified as "XL" , "xl", "E XTRA
LOAD", or "RF" 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 nom inal d iameter of the bead seat. If
you change your wheel s ize, you w ill have to
purchase new tires to match the new r im di­
ameter.
Rim size designation
means r im diameter and width.
Rim width
means nom inal distance between rim fla nges.
Sidewall
means that portion of a tire between the
tread and bead.
Speed rating (letter code)
means the speed at which a tire is designed to
be driven for extended periods of time. The
ratings range from 93 mph (150 km/h) to
186 mph (298 km/h)
~ page 200 . You may
not find this information on all tires because
it is not requ ired by law.
T he speed rating letter code, where applica­
ble, is molded on the tire sidewall and indi­
cates the maximum pe rm issib le road speeds
~ .&. in Winter tires on page 204.
Tire pressure monitoring system
means a system that detects when one or
more of a veh icle's tires are underinflated and
illuminates a low tire pressure warning tell­
tale.
•
•

192 Tires and wheels
Tread
means that portion of a tire that comes into
contact with the road.
Tread separation
means pull ing away of the tread from the tire
carcass .
Treadwear indicators (TWI)
means the projections within the principal
grooves designed to give a v isual ind ication of
the degrees of wear of the tread. See
~ page 198, Tread Wear Indicator (TWI) for
more informat ion on measuring tire wear.
Uniform Tire Quality Grading
is a tire information system developed by the
United States National Highway Traffic Safety
Administration (NH TSA) that is designed to
help buyers make relative comparisons among
tires. The UTQG is not a safety rating and not a
guarantee that a tir e will last fo r a prescribed
number of miles or perform in a certain way.
It simply gives tire buyers additional informa­
tion to combine w ith other considerations,
such as price, brand loyalty and dea ler recom­
mendations. Under UTQG, tires are graded by
the tire manufacturers in three areas: tread­
wear, tract ion and temperature resistance.
The UTQG information on the tires, molded in­
to the sidewalls .
U.S. DOT Tire Identification Number (TIN)
This is the tire's "serial number" It begins
with the letters "DOT" and indicates that the tire meets a
ll federal standards. The next two
numbers or letters indicate the plant where it
was manufactured, and the last four numbers
represent the week and year of manufacture.
For example,
DOT . .. 2210 ...
means that the tire was produced in the 22nd
week of 2010. The other numbers are market­
ing codes that may or may not be used by the
tire manufacturer . This information is used to
contact consumers if a tire defect requires a
recall.
Vehicle capacity weight
means the rated cargo and luggage load plus
150 lbs. (68 kilograms) times the vehicle's to­
ta l seating capacity as listed on the label lo­
cated on the driver's side B-pillar.
Vehicle maximum load on the tire
means that load on an individua l tire that is
determined by distributing to each axle its
share of the maximum loaded vehicle weight
and dividing by two.
Vehicle normal load on the tire
means that load on an individua l tire that is
determined by distributing to eac h axle its
share of the curb weight, accessory weight,
and normal occupant weight (distributed in
accordance with tab le below ~
page 192)
and dividing by two.
Occupant loading and distribution for vehicle normal load for various designated seating
capacities
I Designated seating capacity, Vehicle normal load,
number of occupants number of occupants
2 2
Normally loaded vehicle,
occupant distribution
•
2 in front

Tires and wheels 193
Cold tire inflation pressure
Tire pressure affects the overall handling, performance and safety of a vehicle.
Fig. 150 Tire pressure label: located on driver's side B·
pillar
Tire pressure generally refers to the amount
of air in a tire that it needs it to do its job and
safely carry the combined load of the entire
vehicle and its contents. Tire pressure is measured in kilopascals (kPa), the interna­
tional measuring unit and in pounds per
square inch (PSI). Tire pressure is based in
part on the vehicle's design and load limit­
the greatest amount of weight that the vehi­
cle can carry safely and the tire size. The prop­
er tire pressure is frequently referred to as the
"recommended cold tire inflation pressure."
Air in the tires expands when the tire heats up
because of internal friction when it flexes in
use. The tire pressure is higher when the tire
has warmed up than when it is "cold." It is the
inflation pressure in a "cold" tire that counts.
Therefore, you should never let air out of a
warm tire to match "cold tire inflation pres­
sure" recommendations. The tires would then be underinflated and could fail suddenly.
Maintaining proper tire pressure is one of the
most important things you can do to help
avoid sudden tire failure. Underinflated tires
are a major cause of sudden tire failure. Keep­
ing tires at the right pressure is also impor­
tant for safe and responsive vehicle handling,
traction, braking and load carrying .
Tire pres­
sures are particularly important when the
vehicle is being driven at higher speeds, and
then especially when heavily loaded even
within the permissible load-carrying capaci­
ties approved for your vehicle.
"' ..,
-~ --------------- ~ a ;l!; TIRE AND LOADING INFORMATION
• (SfATING CAPAOTY JOTAI. I }ROHT I :CUITTR I :R£AR I)
l'hl!o combned~c:loo:upain.sanoatg0,sbo&AdnM'fexeeC1 •"'.gcw -b.
COI.O TIRE PRESSURE
- KPa.- PSI
- KPa,- PSI
_ KPa,. PSI
Fig. 151 Tire pressure label
SEE OWNER'S
MANUA L FOR
ADDITTONAL
INFOl<lMATION
n
u
The recommended tire pressures for your Audi
depend on the kind of tires on your vehicle
and the number of passe ngers and/or amount
of luggage you will be transporting.
The tire pressure label located on driver's side
B-pillar on your Audi lists the recommended
cold tire inflation pressures for the vehicle at
its maximum capacity weight and tires that
were on your vehicle at the time it was manu­
factured.
If you wish to improve comfort when operat­
ing the vehicle at normal load (up to 2 occu­
pants), you can adjust tire pressures to those
specified for normal vehicle load. Before oper­
ating the vehicle at maximum load, you must
increase the tire pressures to those specified
for maximum vehicle load
9 .&.
Bear in mind that the tire pressure monitoring
system can only monitor the tire pressures
that are stored. The system does not recog­
nize the load condition of your vehicle.
See the illustration,:;,
fig. 150 for the location
of the label on driver's side B-pillar (color of
the actual label and exact location on the ve­
hicle will vary slightly).
Note that the following table is accurate at
the time of going to press and is subject to
change. In the event of discrepancies, the tire
pressure label on driver's side B-pillar always
ta kes precedence. ..,.

194 Tire s and wheel s
The table be low lists the recommended cold
tire inflation pressures for the Audi model
covered by your Owner's Literature at the vehi- cle's capacity weight and the tire sizes instal­
led on the respective models as original
equipment, or as a factory option.
Engine
(dis­
place­
ment in Tire designation
Tire pressure front Tire pressure rear
normal load full load normal load full load condition condition condition condition
liter )
a -cylin­
der
4 .2
inder
5.2 235
/3 5 R1 9 9 1 V
XL
295 /30 R19 100V X L
305 /30 R1 9 10 2V X L
235 /35 R19 91 V X L
295 /30 R1 9 100V XL
305 /30 R19 102V X L
XL= reinf orc ed
PSI
45
Because tec hnical changes may be made to
vehicle equ ipment dur ing the model yea r, a l­
ways compare the tire size designation on the
tire pressure labe l on you r vehi cle w it h the
tires on your vehicle. Make s ure that the ti re
size information on the veh icle label is the
same as the size of the tires on the vehicle.
This is especially important if the vehicle be­
longs to someone else or you bought the vehi­
cle with different rims/tires or you bought the
vehicle as a previously owned vehicle.
Remember, your safety and that of your pas­
sengers also depends on mak ing sure that
load limits are not exceeded. Vehicle load in­
cludes everybody and everything in and on the
veh icle . These load lim its are technically refer­
red to as the vehicle's G ross Vehicle We ight
Rati ng ("GVWR"). The G ross Ax le Weight Rat­
i ng ("GAWR") is the max imum load that can
be app lied at each o f the veh icle's two axles.
The G ross Vehicle Weight Rating and the
Gross Axle Weight Rating are listed on the
safety compliance stic ker labe l located either
on the driver's side B-pillar. The tire pressure
labe l on your Audi lists the maximum com­
b ined weight of all of the occupants and lug­
gage or other cargo that the veh icle can carry.
For the location of the tire pressure label
¢ fig. 15 0 .
kPA PSI kPA PSI
310 45 310
41
41
kPA PSI
280 41
280 41
kPA
280
280
280
280
.&_ WARNING
Overloading a vehicle can cause loss of ve­
h icle cont ro l, a crash o r other accident, se ­
r ious pe rsonal injury, and even death.
- Ca rrying more we igh t than your veh icle
was designed to carry wi ll prevent the
vehicle from handling properly and in­
crease the risk of a loss of vehicle con­
trol.
- The brakes on a vehicle that has been
overloaded may not be able to stop the
veh icle w ith in a safe distance.
- Tires on a vehicle that has been over load­
ed can fail s uddenly ca us ing loss of con­
trol and a crash.
.&_ WARNING
- Incorrect tire pressures and/or underin­
flation can lead to a serious or fatal acci­
dent.
- Inco rrect tire pressures and/or underin­
f lation cause increased tire wear and can
affect the handling of the vehicle.
- Inco rrect tire pressures and/or underin­
f lation can a lso lead to s udden t ire fail­
ure, including a blowout and sudden de­
flation, ca using loss of veh icle cont ro l.

Checking tire pressure
The correct tire pressure for the tires original­
ly installed on your vehicle is listed on the tire
pressure label located on driver's side 8-pil­ lar.
The recommended t ire pressures are on the
tire pressure label and in the table
r=> page 193, Cold tire inflation pressure . T his
means that the pressure must be checked and
a d ju sted when the tire has not been driven for
mo re than a couple of mi les (kilometers) at
l ow speeds during the p revious three hours.
Air in the tires expands when the tire heats up
as a result of internal fr iction as it flexes in
use. The tire pressure is higher when the tire
h as warmed up than when it is "cold".
It is the inflation pressure in a "cold" tire that
counts. Therefore, you shou ld never let air out
of a warm tire to match "Cold tire inflation pressure" recommendations
c> page 193 . The
tires would then be under infla ted and could
fa il suddenly.
The tire pressure label on yo ur Audi lists t he
recommended cold t ire inflat ion pressures for
the new, or igina l equipment tires that were
on you r vehicle at the t ime it was manufac­
tured. For the location of the label
r=> page 193, fig. 150.
Most tires lose a ir natu rally over time. They
can also lose some a ir if you dr ive ove r a pot­
hole o r hit a curb wh ile pa rking.
It is usua lly
not poss ib le to see whether the radial t ires
used today a re underin flated j ust by looking
at them.
Therefore, be sure to check tire pressures at
least o nce a month and always before going
on a long trip. Make sure to take the number
of people and the amount of luggage into ac­
count when adjusting tire pressure for a trip -
even one that you would not consider to be
"long". See r:=>page 196, Tires and vehicle
load limits for more important information.
Always use an accurate tire pressure gauge
when check ing and adjusting inflation pres­
sures . Check all of the t ires. If the pressure in
Tire s an d wheel s 195
any tire is too high when the tire is "cold", let
air out of the tire slowly with the edge of the
tire ga uge and keep checking the pressure un­
ti l yo u reach the pressure that is correct for
the load (passengers and luggage) and kind of
driv ing you plan to do .
If the pressure in any ti re is too low, note the
difference between the pressure in the cold
tire and the pressure you need and add the air
that you need to reach the correct pressure for
t h e ve hicle load (passenge rs and luggage) for
t h e tires on your vehicle as l isted on the o n
you r vehicle and in this ma nual a nd the k ind
of d riving you plan to do .
Never exceed the max imum inflation pres­
sure li sted on the tire sidewall for any rea­
s on.
Remember that the vehicle manufacturer, not
t h e tire manufactu rer, determines t he cor rect
ti re p ressu re fo r the tires on your ve hicl e.
It is important to check the t ire pressure when
the tires are co ld .
- Read the required tire pressure from the t ire
pressure labe l located on driver's side B-pil­
lar.
- T urn the va lve stem cap counter-clockw ise
to remove it from the tire va lve.
- Place t he air pressure gauge on the va lve.
- The tire pressures should o nly be checked
and ad justed when the tires are co ld . The
slightly raised pressures of warm tires must
not be reduced.
- Adj ust the tire pressure to the load you are
carrying.
- Reinstall the valve stem cap on the va lve.
When should I check the tire pr essu re?
T he co rrect tire pressu re is especially impor­
t a nt a t high speeds. The pressure should
therefore be checked at least once a month
and always before starting a jo urney .
When should I adjust the tire pressures ?
Adjust the tire pressure to the load you a re
ca rrying. After chang ing a wheel
or rep lacing .,..
•
•

196 Tires and wheels
wheels you have to adjust the tire pressures
on all wheels.
A WARNING
Incorrect tire pressures and/or underinfla­
tion can lead sudden tire failure, loss of
control, collision, serious personal injury
or even death.
- When the warning symbol
RI] appears in
the instrument cluster, stop and inspect
the tires .
- Incorrect tire pressure and/or underinfla­
tion can cause increased tire wear and
can affect the handling of the vehicle and
stopping ability .
- Incorrect tire pressures and/or underin­ flation can also lead to sudden tire fail­
ure, including a blowout and sudden de­
flation, causing loss of vehicle control.
- The driver is responsible for the correct
tire pressures for all tires on the vehicle .
The applicable pressure values are locat­
ed on a sticker on the driver's side 8-pil­
lar.
- Only when all tires on the vehicle are fil­
led to the correct pressure, the tire pres­
sure monitoring system can work cor­
rectly.
- The use of incorrect tire pressure values
can lead to accidents or other damage.
Therefore it is essential that the driver
observe the specified tire pressure values
for the tires and the correct pressures for
the function of the tire pressure monitor­
ing system .
- Always inflate tires to the recommended
and correct tire pressure before driving
off .
- Driving with underinflated tires bend
more, letting them get too hot resulting
in tread separation, sudden tire failure
and loss of control.
- Excessive speed and/overloading can
cause heat build-up, sudden tire failure
and loss of control.
- If the tire pressure is too low or too high,
the tires will wear prematurely and the
vehicle will not handle well. -
If the tire is not flat and you do not have
to change a wheel immediately, drive at
reduced speed to the nearest service sta­
tion to check the tire pressure and add
air as required .
(D Note
Driving without valve stem caps can cause
damage to the tire valves. To prevent this,
always make sure that factory installed
valve stem caps on all wheels are securely mounted on the valve.
@ For the sake of the environment
Underinflated tires will also increase the
fuel consumption .
Tires and vehicle load limits
There are limits to the amount of load or
weight that any vehicle and any tire can carry .
A vehicle that is overloaded will not handle
well and is more difficult to stop. Overloading
can not only lead to loss of vehicle control,
but can also damage important parts of the
vehicle and can lead to sudden tire failure, in­ cluding a blowout and sudden deflation that
can cause the vehicle to crash.
Your safety and that of your passengers also depends on making sure that load limits are
not exceeded. Vehicle load includes everybody
and everything in and on the vehicle . These
load limits are technically referred to as the
vehicle 's
Gross Vehicle Weight Rating
("GVWR").
The "GVWR" includes the weight of the basic
vehicle, all factory installed accessories, a full
tank of fuel, oil, coolant and other fluids plus
maximum load. The maximum load includes
the number of passengers that the vehicle is
intended to carry ("seating capacity") with an
assumed weight of 150 lbs. (68 kg) for each
passenger at a designated seating position
and the total weight of any luggage in the ve-
hicle. ..,_

The Gross Axle Weight Rating ("GAWR") is
the maximum load that can be applied at each
of the vehicle's two axles.
The Gross Vehicle Weight Rating and the
Gross Axle Weight Rating are listed on the
safety compliance sticker labe l located on the
driver's side B-pi llar . Your Audi has 2 seat ing
positions in the front for total seat ing capac i­
t y of 2. Each seating posi tion has a safety belt
c::> page 109, Safety belts.
The fact that there is an upper limit to your
ve hicle's Gross Veh icle Weight Rating means
that the total weight of whatever is being car­
ried in the veh icle is limited . The more passen­
gers in the veh icle or passengers who a re
heavier than the standard weights assumed
mean that less weight can be carried as lug­
gage.
The t ire pressure label on your Audi also lists
the maximum combined we ight of all of the
occupants and luggage o r othe r cargo that
the vehicle can carry. For the location of the
la be l
c::>page 193, fig. 150.
A WARNING
Overloading a vehicle can cause loss of ve­
hicle control, a crash or other accident, se­
r ious personal injury, and even death.
- Carrying more weight than your vehicle
was designed to carry will prevent the
vehicle from handling properly and in­
crease the risk of the loss of veh icle con­
trol.
- The brakes on a veh icle that has been
overloaded may not be able to stop the
vehicle within a safe distance .
- Tires on a vehicle that has been overload­
ed can fail suddenly, includ ing a b lowout
and sudden deflation, causing loss of
control and a crash.
Determining correct load limit
Use the example below to cal­
culate the total weight of the
Tires and wheels 197
passengers and luggage or oth­
er things that you plan to trans­
port so that you can make sure
that your vehicle will not be
overloaded.
Steps for Determining
Correct Load Limit
1. Locate the statement "THE
COMBINED WEIGHT OF OC­
CUPANTS AND CARGO
SHOULD NEVER EXCEED XXX
KG OR XXX LBS"on your vehi­
cle's placard (tire inflation
pressure label)
¢ page 193,
fig. 150.
2. Determine the combined weight of the driver and pas­
sengers that will be riding in
your vehicle.
3. Subtract the combined
weight of the driver and pas­
sengers from
"XXX" kilo­
grams or
"XXX" pounds
shown on the sticker
¢ page 193, fig. 150.
4. The resulting figure equals
the available amount of car­
go and luggage load capaci-
ty. For example, if the
"XXX"
amount equals 1400 lbs.
and there will be five 150
lbs. passengers in your vehi­
c le, the amount of available .,..
•
•

198 Tires and wheels
cargo and lugg age load ca­
pacity is 650 lb s. (1400-750
(5
X 150) = 650 lb s.)
5. Determin e the combined
weight of luggage and cargo
being loaded on the vehicle .
That weight may not safely exceed the a vailable cargo
and luggage load capacity
c alculated in Step
4.
6. If your vehicle will be towing
a trailer , load from your trail­
er w ill be tran sferred to your
vehi cle . Consult this manual
to determine how thi s re­
duces the available cargo
and luggage load capacity of
your vehicle.
.,.Che ck the tire sidewall
( ¢ page 199 , fig. 153) to de­
termine the designated load rating for a specific tire.
Tire service life
The service life of tires depends on a lot of
diff erent things i ncluding prop er installation
and balancing, correct tire pressure and driv ·
ing s tyle.
Fig. 152 T ire tread: trea d wea r ind icators (TWI)
Tread Wear Indicator (TWI)
The orig in al tires on yo ur vehi cle ha ve
1/ 16 inch ( 1.6 mm) hig h "wear indica tors"
¢ fig . 152 ru nning acro ss the tread . Depend·
ing on the ma ke , t here will be six to e ight of
them even ly placed aro und the tire. Marks on
t he tire sidewall (for example "TWI" or ot her
symbols) ind icate the pos itions of the tread
wea r indica to rs. Wor n tir es must be rep laced .
Differ ent figures may apply in othe r countries
¢ .&_ .
Tire pressure
Incor rect t ire pressure causes premature wea r
and can cause sudde n tire blow-out . For this
reason, tire pressu re must be checked at least
o nce a month
¢ page 195.
Driving style
Driving fast around c urves, heavy accele rat ion
and hard braking increase tire wear .
Wheel balancing
The wheels on new ve hicles are balance d.
However, va rious s ituations dur ing everyday
driv ing can cause them to become unbal·
anced, resulting in vib rations you can usually
feel t hrough the steer ing whee l.
Unb alanced w hee ls m ust be rebalance d to
avo id excessive wear on steering, suspension
and ti res. A whee l m ust also be reba lanced
whe n a new tire is insta lled.
Incorrect wheel alignment
Incor rect wheel alig nment can cause exces ­
s ive tire wear , impa iring the safety of the vehi ­
cle.
If tires show excessive wear , have the
w hee l alignment chec ked by an authoriz ed
Audi deal er or qualified wo rksh op.
All-wheel drive
Only the wheel/ti re sizes specif ied by the
manufacture r may be used on veh icles with
all-wheel drive. For detai ls see ¢
page 155.

A WARNING
Sudden tire failure can lead to loss of con­
trol, a crash and serious personal injury!
- Never drive a vehicle when the tread on
any tire is worn down to the wear indica­
tors.
- Worn tires are a safety hazard, they do
not grip well on wet roads and increase
your risk of "hydroplaning" and loss of
control.
- Always keep chemicals that can cause
tire damage, such as grease, oil, gasoline
and brake fluid away from t ires.
- Tires age even if they are not be ing used
and can fail suddenly, especially at high
speeds . Tir es that are more than 6 years
old can only be used in an emergency
and then with special care and at lower
speeds.
- Never mount used tires on your vehicle if
you are not sure of their" previous histo ­
ry ." Old used tires may have been dam­
aged even though the damage cannot be
seen that can lead to sudden tire failure
and loss of vehicle control.
Tires and wheels 199
New tires and replacing tires and wheels
New tires and wheels have to be broken in .
Fig. 153 Tir e specificat ion codes on t he s idewall o f a
tire
No. Description
CD Passenger car tire (where applicable)
@ Nominal w idth of tire in millimeters
® Ratio of height to width (aspect ratio)
© Radial
® Rim diameter code
® Load index and speed rating
(f) U.S. DOT tire identification number
® Audi Origina l tire
® Severe snow conditions
@ T ire ply composition and materials
used
@ Maximum load rating
@ Treadwear, traction and temperature
grades
@ Maximum permissible inflation pres-
sure
The tires and rims are essential parts of the
vehicle's design . The tires and rims approved
by Audi are spec ially matched to the charac­
teristics of the vehicle and can make a major .,.
•

200 Tires and wheels
contribution to good road holding and safe
handling when in good condition and properly
inflated
¢ ,& .
We recommend that all work on tires and
wheels be performed by an authorized Audi
dealer. They are familiar with recommended
procedures and have the necessary special
tools and spare parts as well as the proper fa­
cilities for disposing of the old tires.
Authorized Audi dealers have the necessary
information about technical requirements for
installing or changing tires and rims.
Replacing tires and wheels
Tires should be replaced at least in pairs and
not individually (for example both front tires
or both rear tires together).
Be sure to read and heed the information to
the tire pressure monitoring system
¢page 201.
Always buy replacement radial tires that have
the same specifications as the tires approved
for your vehicle by Audi. Replacement tires
must always have the same load rating speci­
fication as the original equipment or approved optional tires listed in the table
¢page 193.
Audi-approved specification tires are specially
matched to your vehicle and its load limits,
and can contribute to the important road hold­
ing, driving characteristics, and safety of the
vehicle. The table(¢
page 193) lists specifica­
tions of the tires approved for the Audi mod­
els covered by your Owner's Literature .
The tire pressure label located on driver's side
B-pillar (
¢ page 193, fig. 151) lists the speci­
f ications of the original equipment tires in­
stalled on your vehicle at the time it was man­
ufactured.
Federal law requires tire manufacturers to
place standardized information on the side­
wall of all tires¢
fig. 153. This information
identifies and describes the fundamental
characteristics, the quality grade of the tire
and also provides a tire identification number for
safety standard certification and in case of
a recall.
Tire specifications
Knowledge of tire specifications makes it eas­
ier to choose the correct tires. Radial tires
have the tire specifications marked on the
sidewall, for example:
P235 / 35 R 18 91 Y
This contains the following information:
P Indicates the tire is for passenger cars
235 Nominal tire width in mm of the tire
from sidewall edge to sidewall edge. In general, the larger the number, the wider
the tire
35 Height/width ratio in percent (aspect ra-
tio)
R Tire construction: Radial
18 Rim diameter code (in inches)
91 Load rating code
Y Speed rating letter code
XL (or "xl", "EXTRA LOAD", or "RF") indicates
that the tire is a"Reinforced" or an "Extra
Load" tire
M+S (or "M/S") Indicates that the tire has
some mud and snow capability
The tires could also have the information of
direction of rotation¢
page 189.
Tire manufacturing date
The manufacturing date is also indicated on
the tire sidewall (possibly only on the
inner
side of the wheel):
"DOT ... 2210 ... " means, for example, that
the tire was produced in the 22nd week of 2010.
Speed rating (letter code)
The speed rating letter code on the wheels in­
dicates the maximum permissible road speeds
¢ .&. in Winter tires on page 204.
P up to 93 mph (150 km/h)
Q up to 99 mph (158 km/h)
R up to 106 mph (170 km/h)
S up to 110 mph (180 km/h)