Get Wheels and tires -> Definition of terms for tires and loading Guide for Mercedes GLA SUV First Generation (2013-2019)

Tire characteristics

This information describes the tire cord and

the number of layers in sidewall : and under

tire tread ;.

Tire data is vehicle-specific and may devi-

ate from the data in the example.

Definition of terms for tires and load-

ing

Tire ply composition and material

used

Describes the number of plies or the number

of layers of rubber-coated fabric in the tire

tread and sidewall. These are made of steel,

nylon, polyester and other materials.

Bar

Metric unit for tire pressure. 14.5038 pounds

per square inch (psi) and 100 kilopascals

(kPa) are the equivalent of 1 bar.

DOT (Department of Transportation)

DOT marked tires fulfill the requirements of

the Canadian Transport Ministry.

Normal occupant weight

The number of occupants for which the vehi-

cle is designed multiplied by 68 kilograms

(150 lb).

Uniform Tire Quality Grading Stand-

ards

A uniform standard to grade the quality of

tires with regards to tread quality, tire traction

and temperature characteristics. Ratings are

determined by tire manufacturers using U.S.

government testing procedures. The ratings

are molded into the sidewall of the tire.

Recommended tire pressure

The recommended tire pressure applies to

the tires mounted at the factory.

The Tire and Loading Information placard con-

tains the recommended tire pressures for

cold tires on a fully loaded vehicle and for the

maximum permissible vehicle speed.

The tire pressure table contains the recom-

mended pressures for cold tires for various

operating conditions, i.e. differing load and

speed conditions.

Increased vehicle weight due to

optional equipment

This is the combined weight of all standard

and optional equipment available for the vehi-

cle, regardless of whether it is actually instal-

led on the vehicle or not.

Rim

This is the part of the wheel on which the tire

is mounted.

GAWR (Gross Axle Weight Rating)

The GAWR is the maximum gross axle weight

rating. The actual load on an axle must never

exceed the gross axle weight rating. The

gross axle weight rating can be found on the

vehicle identification plate on the B-pillar on

the driver's side.

Definition of terms for tires and loading

345

Wheels and tires

Speed rating

The speed rating is part of the tire identifica-

tion. It specifies the speed range for which the

tire is approved.

GVW (Gross Vehicle Weight)

The gross vehicle weight includes the weight

of the vehicle including fuel, tools, the spare

wheel, accessories installed, occupants, lug-

gage and the drawbar noseweight, if applica-

ble. The gross vehicle weight must not exceed

the gross vehicle weight rating GVWR as

specified on the vehicle identification plate on

the B-pillar on the driver's side.

GVWR (Gross Vehicle Weight Rating)

The GVWR is the maximum permissible gross

weight of a fully loaded vehicle (the weight of

the vehicle including all accessories, occu-

pants, fuel, luggage and the drawbar nose-

weight, if applicable). The gross vehicle

weight rating is specified on the vehicle iden-

tification plate on the B-pillar on the driver's

side.

Maximum loaded vehicle weight

The maximum weight is the sum of:

the curb weight of the vehicle

the weight of the accessories

the load limit

the weight of the factory installed optional

equipment

Kilopascal (kPa)

Metric unit for tire pressure. 6.9 kPa corre-

sponds to 1 psi. Another unit for tire pressure

is bar. 100 kilopascal (kPa) is the equivalent

of 1 bar.

Load index

In addition to the load-bearing index, the load

index may also be imprinted on the sidewall of

the tire. This specifies the load-bearing capa-

city more precisely.

Curb weight

The weight of a vehicle with standard equip-

ment including the maximum capacity of fuel,

oil and coolant. It also includes the air-condi-

tioning system and optional equipment if

these are installed in the vehicle, but does not

include passengers or luggage.

Maximum load rating

The maximum load rating in kilograms or

pounds is the maximum weight for which a

tire is approved.

Maximum permissible tire pressure

Maximum permissible tire pressure for one

tire.

Maximum load on one tire

Maximum load on one tire. This is calculated

by dividing the maximum axle load of one axle

by two.

PSI (pounds per square inch)

A standard unit of measure for tire pressure.

Aspect ratio

Relationship between tire height and tire

width in percent.

346

Definition of terms for tires and loading

Wheels and tires

Tire pressure

This is pressure inside the tire applying an

outward force to each square inch of the tire's

surface. The tire pressure is specified in

pounds per square inch (psi), in kilopascal

(kPa) or in bar. The tire pressure should only

be corrected when the tires are cold.

Tire pressure of cold tires

The tires are cold:

if the vehicle has been parked without

direct sunlight on the tires for at least three

hours and

if the vehicle has not been driven further

than 1 mile (1.6 km)

Tread

The part of the tire that comes into contact

with the road.

Bead

The tire bead ensures that the tire sits

securely on the wheel. There are several steel

wires in the bead to prevent the tire from

coming loose from the wheel rim.

Sidewall

The part of the tire between the tread and the

bead.

Weight of optional extras

The combined weight of those optional extras

that weigh more than the replaced standard

part and more than 2.3 kg (5 lbs). These

optional extras, such as high-performance

brakes, level control, a roof rack or a high-

performance battery, are not included in the

curb weight and the weight of the accesso-

ries.

TIN (Tire Identification Number)

This is a unique identifier which can be used

by a tire manufacturer to identify tires, for

example for a product recall, and thus identify

the purchasers. The TIN is made up of the

manufacturer's identity code, tire size, tire

type code and the manufacturing date.

Load bearing index

The load bearing index (also load index) is a

code that contains the maximum load bearing

capacity of a tire.

Traction

Traction is the result of friction between the

tires and the road surface.

Treadwear indicators

Narrow bars (tread wear bars) that are dis-

tributed over the tire tread. If the tire tread is

level with the bars, the wear limit of á in

(1.6 mm) has been reached.

Occupant distribution

The distribution of occupants in a vehicle at

their designated seating positions.

Total load limit

Nominal load and luggage load plus

68 kilograms (150 lb) multiplied by the num-

ber of seats in the vehicle.

Changing a wheel

Flat tire

You can find information on what to do in the

event of a flat tire in the "Flat tire" section

(Y page 306). Information on driving with

MOExtended tires in the event of a flat tire can

Changing a wheel

347

Wheels and tires

Wheels and tires -> Definition of terms for tires and loading for Your Mercedes GLA SUV First Generation (2013-2019)

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