2008 SMART FORTWO COUPE Owners Manual

Tires and wheels
200
>> Operation Load identification
1
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
identification1 may be molded into the tire
sidewall following the letter designating the
tire speed rating (

page 196).No specification given: absence of any text
(like in above example) indicates a standard
load (SL) tire.
XL (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 speci

fied 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.
The TIN is a unique identifier which facilitates
efforts by tire manufactures 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".
1
DOT
2
Manufacturer’s identification mark
3
Tire size
4
Tire type code (at the option of the tire
manufacturer)
5
Date of manufacture
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may
vary from data shown in above illustration.

Tires and wheels
>> Operation
201
DOT (D
epartment o
f T
ransportation)
Tire branding symbol1 (

page 200) which
denotes the tire meets requirements of the
U.S. Department of Transportation.
Manufacturer’s identification mark
Manufacturer’s identification mark2
(

page 200) denotes the tire manufacturer.
New tires have a mark with two symbols.
Retreaded tires have a mark with four
symbols. For more information on retreaded
tires (

page 182).
Tire size
Code3 (
page 200) indicates the tire size.
Tire type code
Code4 (
page 200) may, at the option of
the manufacturer, be used as a descriptive
code for identifying significant characteris

tics of the tire.
Date of manufacture
Date of manufacture5 (

page 200)
identifies the week and year of manufacture.The first two figures identify the week, start

ing with "01" to represent the first full week of
the calendar year. The second two figures
represent the year.
For example, "3202" represents the 32nd
week of 2002.
Maximum tire load
1
Maximum tire load rating
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may
vary from data shown in above illustration.The maximum tire load is the maximum weight
the tires are designed to support.
For more information on tire load rating
(

page 197).
For information on calculating total and cargo
load capacities (

page 187).
G
Warning!
Do not overload the tires by exceeding
the specified load limit as indicated on
the Tire and Loading Information placard
located on the driver’s door B
pillar.
Overloading the tires can overheat them,
possibly causing a blowout. Overloading
the tires can also result in handling or
steering problems, or brake failure.

Tires and wheels
202
>> Operation Maximum tire inflation pressure
1
Maximum permissible tire inflation
pressure
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may
vary from data shown in above illustration.
This is the maximum permissible tire inflation
pressure for the tire.Always follow the recommended tire inflation
pressure (

page 189) for proper tire infla

tion.Uniform Tire Quality Grading Standards
(U.S. vehicles)
Tire manufacturers are required to grade
tires based on three performance factors:
treadwear, traction and temperature resis

tance.
1
Treadwear
2
Traction
3
Temperature resistance
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may
vary from data shown in above illustration.
G
Warning!
Never exceed the max. tire inflation
pressure. Follow recommended tire
inflation pressures.
Do not underinflate tires. Underinflated
tires wear excessively and/or unevenly,
adversely affect handling and fuel econ

omy, and are more likely to fail from being
overheated.
Do not overinflate tires. Overinflated
tires can adversely affect handling and
ride comfort, wear unevenly, increase
stopping distance, and result in sudden
deflation (blowout) because they are
more likely to become punctured or
damaged by road debris, potholes etc.

Tires and wheels
>> Operation
203
Quality grades can be found, where applica

ble, on the tire sidewall between tread shoul

der and maximum section width. For example:
All passenger car tires must conform to fed

eral safety requirements in addition to these
grades.
Treadwear
The treadwear grade is a comparative rating
based on the wear rate of the tire when tested
under controlled conditions on a specified
government test course.
For example, a tire graded 150 would wear
one and one
half (1
1/2) times as well on the
government course as a tire graded 100.
The relative performance of tires depends
upon the actual conditions of their use,
however, and may depart significantly from
the norm due to variations in driving habits,
service practices and differences in road
characteristics and climate.Traction
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
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 corre

sponds 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.
Treadwear
Traction
Temperature
200
AA
A
G
Warning!
The traction grade assigned to this tire is
based on straight
ahead braking trac

tion tests, and does not include acceler

ation, cornering, hydroplaning, or peak
traction characteristics.
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 load

ing, either separately or in combination,
can cause excessive heat build
up and
possible tire failure.

Tires and wheels
204
>> Operation Tire ply material
1
Plies in sidewall
2
Plies under tread
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may
vary from data shown in above illustration.
This marking tells you about the type of cord
and number of plies in the sidewall and under
the tread.
Tire and loading terminologyAccessory weight
The combined weight (in excess of those stan

dard items which may be replaced) of auto

matic transmission, power steering, power
brakes, power windows, power seats, 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 per

centage.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 equip

ment, but without passengers and cargo.

Tires and wheels
>> Operation
205
DOT (D
epartment o
f T
ransportation)
A tire branding symbol which denotes the tire
meets requirements of the U.S. Department of
Transportation
GAWR (G
ross A
xle W
eight R
ating)
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 (G
ross V
ehicle W
eight)
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 certifi

cation label located on the driver’s door
B
pillar.GVWR (G
ross V
ehicle W
eight R
ating)
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.
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 regu

lar production options weighing over 5 lbs
(2.3 kilograms) in excess of those standard
items which they replace, not previously con

sidered in curb weight or accessory weight,
including heavy duty brakes, ride levelers,
roof rack, heavy duty battery, and special
trim.

Tires and wheels
206
>> Operation PSI (Pounds per s
quare i
nch)
A standard unit of measure for air pressure

> bar, kilopascal (kPa).
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 (T
ire I
dentification N
umber)
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 num

ber 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, poly

ester, 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.
Treadwear indicators
Narrow bands, sometimes called "wear bars"
that show across the tread of a tire when only
1/16in (1.6 mm) of tread remains.

Tires and wheels
>> Operation
207
Uniform Tire Quality Grading Standards
A tire information system that provides
consumers with ratings for a tire’s traction,
temperature and treadwear. Ratings are
determined by tire manufacturers using
government testing procedures. The ratings
are molded into the sidewall of the tire.
Vehicle maximum load on the tire
Load on an individual tire that is determined
by distributing to each axle its share of the
maximum loaded vehicle weight and dividing it
by two.
Rotating tiresThoroughly clean the mounting face of the
wheels and brake disks, i.e. the inner side of
the wheels/tires each time the wheels/tires
are changed. Check for and ensure proper
tire inflation pressure.For information on wheel change, see "Flat
tire" (

page 265).
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.
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.