MERCEDES-BENZ GLA 2019 Owners Manual

All about wheels and tires
Uniform Tire Quality Grading Stand-
ards
Overview of Tire Quality Grading
Standards
Uniform Tire Quality Grading Standards areU.S. government specifications. Their purposeis to provide drivers with uniform reliable infor-mation on tire performance data. Tire manu-facturers have to grade tires using three per-formance factors:Ctread wear grade,Dtraction grade and

tion, 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 thegeneration of heat and its ability to dissipateheat when tested under controlled conditionson a specified indoor laboratory test wheel.Sustained high temperature can cause thematerial of the tire to degenerate and reducetire life, and excessive temperature can lead tosudden tire failure. The grade C correspondsto a level of performance which all passengercar tires must meet under the Federal MotorVehicle Safety Standard No. 109. Grades Band A represent higher levels of performanceon the laboratory test wheel than the minimumrequired by law.
Tire labeling
Overview
CUniform Tire Quality Grading Standards(Ypage 323)
DDepartment of Transportation, Tire Identifi-cation Number (Ypage 322)

If "LT" precedes the size description: these arelight truck tires according to U.S. manufactur-ing standards.
If "T" precedes the size description: compactemergency wheels with high tire pressure thatare only designed for temporary use in anemergency.
Tire width:tire widthCshows the nominaltire width in millimeters.
Aspect ratio:aspect ratioDis the size ratiobetween the tire height and tire width and isshown in percent. The aspect ratio is calcula-ted by dividing the tire width by the tire height.
Tire code:tire code

All-weather tires and winter tires
IndexSpeed rating
Q M+S1up to 100 mph (160 km/h)
T M+S1up to 118 mph (190 km/h)
H M+S1up to 130 mph (210 km/h)
V M+S1up to 149 mph (240 km/h)
iNot all tires with the M+S marking providethe driving characteristics of winter tires. Inaddition to the M+S marking, winter tiresalso have theMsnowflake symbol on thetire wall. Tires with this marking fulfill therequirements of the Rubber ManufacturersAssociation (RMA) and the Rubber Associa-tion of Canada (RAC) regarding the tire trac-tion on snow. They have been especiallydeveloped for driving on snow.
An electronic speed limiter prevents your vehi-cle from exceeding a speed of 130 mph(210 km/h).
The speed rating of tires mounted at the fac-tory may be higher than the maximum speedthat the electronic speed limiter permits.
Make sure that your tires have the requiredspeed rating, e.g. when buying new tires. Therequired speed rating for your vehicle can befound in the "Tires" section (Ypage 329).
Further information about reading tire datacan be obtained from any qualified specialistworkshop.
Load index
In addition to the load-bearing index, loadindexCmay be imprinted after the letters
that identify speed rating on the sidewall ofthe tire. Speed rating (Ypage 320).
RIf no specification is given: no text (as in theexample above), represents a standard load(SL) tire
RXL or Extra Load: represents a reinforcedtire
RLight Load: represents a light load tire
RC, D, E: represents a load range thatdepends on the maximum load that the tirecan carry at a certain pressure
iTire data is vehicle-specific and may devi-ate from the data in the example.
Maximum load rating
Maximum tire loadCis the maximum permis-sible weight for which the tire is approved.
Do not overload the tires by exceeding thespecified load limit. The maximum permissibleload can be found on the vehicle's Tire andLoading Information placard on the B-pillar onthe driver's side (Ypage 316).
iThe actual values for tires are vehicle-spe-cific and may deviate from the values in theillustration.
DOT, Tire Identification Number (TIN)
US tire regulations stipulate that every tiremanufacturer or retreader must imprint a TINin or on the sidewall of each tire produced.
1Or M+SMfor winter tires.
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Wheels and tires

The TIN is a unique identification number. TheTIN enables the tire manufacturers or retread-ers to inform purchasers of recalls and othersafety-relevant matters. It makes it possiblefor the purchaser to easily identify the affectedtires.
The TIN is made up of manufacturer identifica-tion codeD, tire size

Recommended tire pressures
The recommended tire pressure applies to thetires mounted at the factory.
The Tire and Loading Information placard con-tains the recommended tire pressures for coldtires on a fully loaded vehicle and for the maxi-mum permissible vehicle speed.
The tire pressure table contains the recom-mended pressures for cold tires for variousoperating conditions, i.e. differing load andspeed conditions.
Increased vehicle weight due to optional
equipment
The combined weight of all standard andoptional equipment available for the vehicle,regardless of whether it is actually installed onthe vehicle or not.
Rim
This is the part of the wheel on which the tireis mounted.
GAWR (Gross Axle Weight Rating)
The GAWR is the maximum gross axle weightrating. The actual load on an axle must neverexceed the gross axle weight rating. The grossaxle weight rating can be found on the vehicleidentification plate on the B-pillar on the driv-er's side.
Speed rating
The speed rating is part of the tire identifica-tion. It specifies the speed range for which thetire is approved.
GVW (Gross Vehicle Weight)
The gross vehicle weight includes the weightof the vehicle including fuel, tools, the sparewheel, accessories installed, occupants, lug-gage and the drawbar noseweight, if applica-ble. The gross vehicle weight must not exceedthe gross vehicle weight rating GVWR as speci-fied on the vehicle identification plate on theB-pillar on the driver's side.
GVWR (Gross Vehicle Weight Rating)
The GVWR is the maximum permissible grossweight of a fully loaded vehicle (the weight ofthe vehicle including all accessories, occu-pants, fuel, luggage and the drawbar nose-weight, if applicable). The gross vehicle weightrating is specified on the vehicle identificationplate on the B-pillar on the driver's side.
Maximum loaded vehicle weight
The maximum weight is the sum of:
Rthe curb weight of the vehicle
Rthe weight of the accessories
Rthe load limit
Rthe weight of the factory installed optionalequipment
Kilopascal (kPa)
Metric unit for tire pressure. 6.9 kPa corre-sponds to 1 psi. Another unit for tire pressureis bar. 100 kilopascals (kPa) are the equivalentof 1 bar.
Load index
In addition to the load-bearing index, the loadindex may also be imprinted on the sidewall ofthe 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 theseare installed in the vehicle, but does notinclude passengers or luggage.
Maximum load rating
The maximum tire load is the maximum per-missible weight in kilograms or lbs for which atire is approved.
Maximum permissible tire pressure
Maximum permissible tire pressure for onetire.
Maximum load on one tire
Maximum load on one tire. This is calculatedby dividing the maximum axle load of one axleby two.
PSI (pounds per square inch)
A standard unit of measure for tire pressure.
Aspect ratio
Relationship between tire height and tire widthin percent.
Tire pressure
This is pressure inside the tire applying an out-ward force to each square inch of the tire'ssurface. The tire pressure is specified in
324All about wheels and tires
Wheels and tires

pounds per square inch (psi), in kilopascal(kPa) or in bar. The tire pressure should onlybe corrected when the tires are cold.
Cold tire pressure
The tires are cold:
Rif the vehicle has been parked with the tiresout of direct sunlight for at least three hoursand
Rif the vehicle has not been driven furtherthan 1 mile (1.6 km)
Tread
The part of the tire that comes into contactwith the road.
Bead
The tire bead ensures that the tire sitssecurely on the wheel. There are several steelwires in the bead to prevent the tire from com-ing loose from the wheel rim.
Sidewall
The part of the tire between the tread and thebead.
Weight of optional extras
The combined weight of those optional extrasthat weigh more than the replaced standardparts and more than 2.3 kg (5 lbs). Theseoptional extras, such as high-performancebrakes, level control, a roof rack or a high-per-formance battery, are not included in the curbweight and the weight of the accessories.
TIN (Tire Identification Number)
This is a unique identifier which can be usedby a tire manufacturer to identify tires, forexample for a product recall, and thus identifythe purchasers. The TIN is made up of themanufacturer's identity code, tire size, tiretype code and the manufacturing date.
Load bearing index
The load bearing index (also load index) is acode that contains the maximum load bearingcapacity of a tire.
Traction
Traction is the result of friction between thetires and the road surface.
Treadwear indicators
Narrow bars (tread wear bars) that are distrib-uted over the tire tread. If the tire tread is levelwith the bars, the wear limit of

The wear patterns on the front and rear tiresdiffer, depending on the operating conditions.Rotate the wheels before a clear wear patternhas formed on the tires. Front tires typicallywear more on the shoulders and the rear tiresin the center.
On vehicles that have the same size front andrear wheels, you can rotate the wheels accord-ing to the intervals in the tire manufacturer'swarranty book in your vehicle documents. If nowarranty book is available, the tires should berotated every 3,000 to 6,000 miles (5,000 to10,000 km). Depending on tire wear, this maybe required earlier. Do not change the direc-tion of wheel rotation.
Clean the contact surfaces of the wheel andthe brake disc thoroughly every time a wheelis rotated. Check the tire pressure and, if nec-essary, restart the tire pressure loss warningsystem (Canada only) or the tire pressuremonitor (USA only).
Direction of rotation
Tires with a specified direction of rotation haveadditional benefits, e.g. if there is a risk ofhydroplaning. These advantages can only begained if the tires are installed correspondingto the direction of rotation.
An arrow on the sidewall of the tire indicatesits correct direction of rotation.
Storing wheels
Store wheels that are not being used in a cool,dry and preferably dark place. Protect the tiresfrom oil, grease, gasoline and diesel.
Mounting a wheel
Preparing the vehicle
XStop the vehicle on solid, non-slippery andlevel ground.
XApply the electric parking brake manually.
XBring the front wheels into the straight-ahead position.
XShift the transmission to position].
XSwitch off the engine.
XVehicles without KEYLESS-GO:removethe SmartKey from the ignition lock.
XVehicles with KEYLESS-GO start-func-tion or KEYLESS-GO:open the driver'sdoor.The vehicle electronics are now in position

XFold both plates upC.
XFold out lower plateD.
XGuide the lugs on the lower plate fully intothe openings in base plate

Jacking points
The jacking points are located just behind thefront wheel housings and just in front of therear wheel housings (arrows).
XTake ratchet wrench