The traction grades, from highest to
lowest, are AA, A, B, and C. Those grades
represent the tire’s ability to stop on wet
pavement as measured under controlled
conditions on specified government test
surfaces of asphalt and concrete. A tire
marked C may have poor traction
performance.
Temperature
G
WARNING
The temperature grade for this tire is
established for a tire that is properly
inflated and not overloaded. Excessive
speed, underinflation, or excessive
loading, either separately or in
combination, can cause excessive heat
build-up and possible tire failure.
The
temperature grades are A (the highest),
B, and C, representing the tire’s resistance
to the generation of heat and its ability to
dissipate heat when tested under
controlled conditions on a specified
indoor laboratory test wheel. Sustained
high temperature can cause the material of
the tire to degenerate and reduce tire life,
and excessive temperature can lead to
sudden tire failure. The grade C
corresponds to a level of performance
which all passenger car tires must meet
under the Federal Motor Vehicle Safety
Standard No. 109. Grades B and A represent
higher levels of performance on the
laboratory test wheel than the minimum
required by law. Rotating tires
G
WARNING
Do not rotate front and rear wheels as they
have different dimensions, e.g. rim size,
wheel offset etc. Otherwise, the handling
can be affected and you could endanger
yourself and others. Thoroughly clean the mounting face of the
wheels
and brake discs, i.e. the inner side
of the wheels/tires each time the wheels/
tires are changed. Check for and ensure
proper tire inflation pressure. G
WARNING
Have the tightening torque checked after
changing a wheel. Wheels could become
loose if not tightened with a torque of
81 lb‑ft (110 Nm).
Only use genuine smart wheel bolts
specified for your vehicle’s rims.
For
information on wheel change, see “Flat
tire” (Y page 186). Tire labeling
Besides tire name (sales designation) and
manufacturer name, a number of markings
can be found on a tire.
Following are some explanations for the
markings on your vehicle’s tires: :
Uniform Quality Grading Standards
(Y page 134)
; DOT, Tire Identification Number (TIN)
(Y page 138)
= Maximum tire load (Y page 132)
? Maximum tire inflation pressure
(Y page 129) Tires and wheels
135
>> Operation. Z
A
Manufacturer
B Tire ply material ( Y page 139)
C Tire size designation, load and speed
rating (Y page 136)
D Load identification (Y page 138)
E Tire name
i For illustration purposes only. Actual
data
on tires are specific to each vehicle
and may vary from data shown in above
illustration.
For more information, see “Rims and
tires” ( Y page 217).
Tire size designation, load and speed
rating :
Tire width
; Aspect ratio in %
= Radial tire code
? Rim diameter
A Tire load rating
B Tire speed rating
i For information purposes only. Actual
data
on tires are specific to each vehicle
and may vary from data shown in above
illustration.
General:
Depending on the design standards used,
the tire size molded into the sidewall may
have no letter or a letter preceding the tire
size designation. No letter preceding the size designation
(as illustrated above): Passenger car tire
based on European design standards.
Letter
“P” preceding the size designation:
Passenger car tire based on U.S. design
standards.
Letter “LT” preceding the size
designation: Light Truck tire based on U.S.
design standards.
Letter “T” preceding the size designation:
Temporary spare tires which are high
pressure compact spares designed for
temporary emergency use only.
Tire width
Tire width : indicates the nominal tire
width in mm.
Aspect ratio
Aspect ratio ; is the dimensional
relationship between tire section height
and section width and is expressed as a
percentage. The aspect ratio is arrived at
by dividing section height by section
width.
Tire code
Tire code = indicates the tire
construction type. The “R” stands for radial
tire type. Letter “D” means diagonal or
bias ply construction; letter “B” means
belted-bias ply construction.
At the tire manufacturer’s option, any tire
with a speed capability above 149 mph
(240 km/h) can include a “ZR” in the size
designation (for example: 245/40 ZR 18).
For additional information, see “Tire
speed rating” (Y page 137).
Rim diameter
Rim diameter ? is the diameter of the
bead seat, not the diameter of the rim edge.
Rim diameter is indicated in inches (in). 136
Tires and wheels
>> Operation.
symbol in the service description.
Example: 245/40 ZR18 97Y.
In this example, “97Y” is the service
description. The letter “Y” designates
the speed rating and the speed
capability of the tire is limited to
186 mph (300 km/h).
R Any tire with a speed capability above
186
mph (300 km/h) must include a “ZR” in
the size designation AND the service
description must be placed in
parenthesis. Example:
275/40 ZR 18 (99Y). The “(Y)” speed rating
in parenthesis designates the maximum
speed capability of the tire as being
above 186 mph (300 km/h). Consult the tire
manufacturer for the actual maximum
permissible speed of the tire.
All-season and winter tires Index Speed rating
Q M+S
15 up to 100 mph (160 km/h)
T M+S
15 up to 118 mph (190 km/h)
H M+S
15 up to 130 mph (210 km/h)
V M+S
15 up to 149 mph (240 km/h)
i
Not
all M+S rated tires provide special
winter performance. Make sure the tires
you use show M+S and the mountain/
snowflake marking i on the tire
sidewall. These tires meet specific snow
traction performance requirements of
the Rubber Manufacturers Association
(RMA) and the Rubber Association of
Canada (RAC) and have been designed
specifically for use in snow conditions. Load identification
i
For illustration purposes only. Actual
data
on tires are specific to each vehicle
and may vary from data shown in above
illustration.
In addition to the tire load rating, special
load identification : may be molded into
the tire sidewall following the letter
designating the tire speed rating B
(Y page 137).
No specification given: absence of any text
(like in above example) indicates a
standard load (SL) tire.
XL or Extra Load: designates an extra load
(or reinforced) tire.
Light Load: designates a light load tire.
C, D, E: designates load range associated
with the maximum load a tire can carry at a
specified pressure. DOT, Tire Identification Number (TIN)
U.S.
tire regulations require each new tire
manufacturer or tire retreader to mold a
TIN into or onto a sidewall of each tire
produced.
15 or M+S i for winter tires.138
Tires and wheels
>> Operation.
radio, and heater, to the extent that these
items are available as factory-installed
equipment (whether installed or not).
Air pressure
The amount of air inside the tire pressing
outward
on each square inch of the tire. Air
pressure is expressed in pounds per square
inch (psi), or kilopascal (kPa) or bars.
Aspect ratio Dimensional relationship between tire
section
height and section width expressed
in percentage.
Bar Another metric unit for air pressure. There
are
14.5038 pounds per square inch (psi) to
1 bar; there are 100 kilopascals (kPa) to
1 bar.
Bead The tire bead contains steel wires wrapped
by steel cords that hold the tire onto the
rim.
Cold tire inflation pressure
Tire inflation pressure when your vehicle
has been sitting for at least 3 hours or
driven no more than 1 mile (1.6 km).
Curb weight
The weight of a motor vehicle with standard
equipment including the maximum
capacity of fuel, oil, and coolant, and, if
so equipped, air conditioning and
additional optional equipment, but
without passengers and cargo.
DOT (Department of Transportation)
A tire branding symbol which denotes the
tire meets requirements of the U.S.
Department of Transportation. GAWR (Gross Axle Weight Rating) The GAWR is the maximum permissible axle
weight. The gross vehicle weight on each
axle must never exceed the GAWR for the
front and rear axle indicated on the
certification
label located on the driver’s
door B‑pillar.
GVW (Gross Vehicle Weight) The GVW comprises the weight of the
vehicle including fuel, tools, installed
accessories, passengers and cargo. The
GVW
must never exceed the GVWR indicated
on the certification label located on the
driver’s door B‑pillar.
GVWR (Gross Vehicle Weight Rating) This is the maximum permissible vehicle
weight of the fully loaded vehicle (weight
of the vehicle including all options,
passengers,
fuel, and cargo. It is indicated
on certification label located on the
driver’s door B‑pillar.
Kilopascal (kPa) The metric unit for air pressure. There are
6.9
kPa to 1 psi; another metric unit for air
pressure is bars. There are
100 kilopascals (kPa) to 1 bar.
Maximum load rating The maximum load in kilograms and pounds
that can be carried by the tire.
Maximum loaded vehicle weight
The sum of curb weight, accessory weight,
total load limit and production options
weight.
Maximum permissible tire inflation
pressure
This number is the greatest amount of air
pressure
that should ever be put in the tire.140
Tires and wheels
>> Operation.
Normal occupant weight
The number of occupants the vehicle is
designed to seat, multiplied by
68 kilograms (150 lbs).
Occupant distribution
The distribution of occupants in a vehicle
at their designated seating positions.
Production options weight
The combined weight of those installed
regular production options weighing over
5 lbs (2.3 kilograms) in excess of those
standard items which they replace, not
previously considered in curb weight or
accessory weight, including heavy duty
brakes,
ride levelers, roof rack, heavy duty
battery, and special trim.
PSI (Pounds per square inch) A standard unit of measure for air
pressure.
Recommended tire inflation pressure
The recommended tire inflation pressure
for
normal driving conditions is listed on
the Tire and Loading Information placard
located on driver’s door B‑pillar and
provides best handling, tread life and
riding comfort.
Rim A metal support for a tire or a tire and tube
assembly upon which the tire beads are
seated.
Sidewall
The portion of a tire between the tread and
the bead. TIN (Tire Identification Number) Unique identifier which facilitates
efforts by tire manufacturers to notify
purchasers in recall situations or other
safety matters concerning tires and gives
purchasers the means to easily identify
such tires. The TIN is comprised of
“Manufacturer’s identification mark”,
“Tire size”, “Tire type code” and “Date of
manufacture”.
Tire load rating
Numerical code associated with the
maximum load a tire can support.
Tire ply composition and material used
This indicates the number of plies or the
number of layers of rubber-coated fabric
in the tire tread and sidewall. Tire
manufacturers also must indicate the ply
materials in the tire and sidewall, which
include
steel, nylon, polyester, and others.
Tire speed rating Part of tire designation; indicates the
speed range for which a tire is approved.
Total load limit
Rated cargo and luggage load plus
68 kilograms (150 lbs) times the vehicle’s
designated seating capacity.
Traction
Force exerted by the vehicle on the road via
the tires. The amount of grip provided.
Tread
The portion of a tire that comes into
contact with the road. Tires and wheels
141
>> Operation. Z
important to keep in mind that a
considerably higher degree of effort is
necessary to brake and steer the vehicle.
Adapt your driving accordingly.
Brakes
G
WARNING
Make sure not to endanger any other road
users when carrying out braking
maneuvers.
Refer to the description of the hydraulic
brake assistant
(Y page 48).
! Because the ESP ®
operates
automatically, the engine must be turned
off (ignition switched off) when the
parking brake is being tested on a brake
test dynamometer. Active braking action
through the ESP ®
may otherwise seriously
damage the brake system which is not
covered by the smart Limited Warranty.
Brake pad wear or a leak in the brake system
may be the reason for low brake fluid level
in the brake fluid reservoir.
The brake fluid level in the brake fluid
reservoir may be too low if the brake
warning lamp in the instrument cluster
comes on (Y page 22) although the parking
brake is released.
Have the brake system inspected
immediately. Contact an authorized smart
center.
All checks and service work on the brake
system should be carried out by qualified
technicians only. Contact an authorized
smart center.
Only install brake pads and use brake fluid
recommended by smart.
Inclines !
When driving down long and steep
grades,
relieve the load on the brakes by
shifting into a lower gear to use the engine’s braking power. This helps
prevent overheating of the brakes and
reduces brake pad wear.
When
using the engine’s braking power, a
drive wheel may not spin for an extended
period of time, e.g. on slippery road
surfaces. This may cause serious damage
to the drive- train which is not covered
by the smart Limited Warranty.
High and low stresses G
WARNING
Resting your foot on the brake pedal will
cause excessive and premature wear of the
brake pads.
It can also result in the brakes
overheating, thereby significantly
reducing their effectiveness and your
ability to stop the vehicle in sufficient
time to avoid an accident.
After
hard braking, it is advisable to drive
on for some time, rather than immediately
park, so that the air stream will cool down
the brakes faster.
If your brake system is normally only
subjected to moderate loads, you should
occasionally test the effectiveness of the
brakes by applying above-normal braking
pressure at higher speeds. This will also
enhance the grip of the brake pads. G
WARNING
Make sure not to endanger any other road
users when carrying out these braking
maneuvers.
Wet road surface G
WARNING
After driving in heavy rain for some time
without applying the brakes or through
water
deep enough to wet brake components,
the first braking action may be somewhat
reduced and increased pedal pressure may
be necessary to obtain expected braking 144
Driving instructions
>> Operation.
effect. Maintain a safe distance from
vehicles in front.
To
help prevent brake disc corrosion after
driving on wet road surfaces (particularly
salted roads), it is advisable to brake the
vehicle with considerable force prior to
parking. The heat generated serves to dry
the brakes. G
WARNING
Make sure not to endanger any other road
users when carrying out these braking
maneuvers.
Limited braking effect on salted roads Remember that the effect of the brakes can
be
limited on salted road surfaces. A layer
of salt can form on brake discs and brake
pads, considerably reducing the friction
between the brake disc and the brake pad.
The effect is most noticeable after long
trips without braking, e.g. on the highway,
and after the vehicle has been parked for
several hours. G
WARNING
The accumulation of salt on brake discs and
brake pads reduces braking effectiveness
and increases the distance necessary to
come to a complete standstill. This could
potentially cause an accident and/or
personal injury.
To avoid this risk, you should
R brake carefully every now and then on
salted
roads in order to remove any layer
of salt on the brake disc and brake pad,
but do so without endangering any other
road users
R keep a good safe distance from the
vehicle in front and drive carefully
R press the brake carefully at the end of the
trip and again when beginning the next
trip in order to remove any salt residues
from the brake disc New brake pads Only install brake pads recommended by
smart.
G
WARNING
If other than recommended brake pads are
installed,
or other than recommended brake
fluid is used, the braking properties of the
vehicle can be degraded to an extent that
safe braking is substantially impaired.
This could result in an accident. G
WARNING
New brake pads will not achieve their
optimal braking effect until after several
hundred miles (kilometers). This means
that you must compensate for the reduced
braking effect by pressing harder on the
brake pedal and adapt your driving style
accordingly. The same applies after brake
pads or brake discs have been changed. Drive sensibly - save fuel
Fuel consumption, to a great extent,
depends on driving habits and operating
conditions.
To save fuel you should:
R Shift gears in a timely manner.
R Avoid frequent acceleration and
deceleration.
R Keep
tires at the recommended inflation
pressures.
R Remove carriers* when not in use.
R Remove unnecessary loads.
R Allow engine to warm up under low load
use.
R Have all maintenance work performed at
the intervals specified in the
Maintenance Booklet and as required by
the Maintenance System. Contact an
authorized smart center.
Fuel consumption is also increased by
driving in cold weather, in stop-and-go
traffic, on short trips, and in hilly areas. Driving instructions
145
>> Operation.
* optional Z
Depending upon the weather and/or road
surface (conditions), the tire traction
varies widely.
Specified
tire inflation pressures must be
maintained. This applies particularly if
the tires are subject to high loads (e.g.
high speeds, heavy loads, high ambient
temperatures). G
WARNING
Do not drive with a flat tire. A flat tire will
affect
your ability to steer or brake and may
cause you to lose control of the vehicle.
Continued driving with a flat tire or
driving at high speed with a flat tire will
cause excessive heat build-up and possibly
a fire.
For more information, see “Tires and
wheels” (Y page 124). Hydroplaning
Depending on the depth of the water layer
on the road, hydroplaning may occur
resulting in a loss of control, even at low
speeds and with new tires. Reduce vehicle
speed, avoid track grooves in the road and
apply
brakes cautiously when it is raining. Tire traction
The
safe speed on a wet, snow covered or icy
road is always lower than on a dry road.
You should pay particular attention to the
condition of the road whenever the outside
temperatures are close to the freezing
point. G
WARNING
If ice has formed on the road, tire traction
will be substantially reduced. Under such
weather
conditions, drive, steer and brake
with extreme caution.
smart recommends winter tires
(Y page 142) with a minimum tread depth of approximately
1
/ 6 in (4 mm) on all four
wheels for the winter season to ensure
normal
balanced handling characteristics.
On packed snow, they can reduce your
stopping distance compared to summer
tires.
Stopping distance, however, is still
considerably greater than when the road is
not covered with snow or ice. Exercise
appropriate caution.
! Avoid spinning of a drive wheel for an
extended period when driving off on
slippery road surfaces. Otherwise, the
drivetrain could be damaged, which is
not covered by the smart Limited
Warranty. Tire speed rating
Regardless of the tire speed rating, local
speed
limits should be obeyed. Use prudent
driving speeds appropriate to prevailing
conditions. G
WARNING
Even when permitted by law, never operate
a vehicle at speeds greater than the
maximum speed rating of the tires.
Exceeding the maximum speed for which
tires are rated can lead to sudden tire
failure,
causing loss of vehicle control and
possibly resulting in an accident and/or
personal injury and possible death, for you
and for others.
An electronic speed limiter prevents your
vehicle from exceeding a speed of 90 mph
(145 km/h).
The factory equipped tires on your vehicle
may have a tire speed rating above the
maximum speed permitted by the
electronic speed limiter.
Make sure your tires have the required tire
speed rating as specified for your vehicle
in the “Technical data section” Driving instructions
147
>> Operation. Z