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Un iform Ti re Quality Grading St andards: a
uniform st andard to gr ade th e qu ality of tires
with re ga rd to tread qu alit y, tire traction and
te mp erature ch aracteristics. The qu ality grading
assessment is made by th e manufacturer fo llow‐
ing specifications from th e U. S. go ve rn ment. The
qu ality gr ade of a tire is imprinted on th e side
wa ll of th e tire.
Re commended tire pressu re : th e re commen‐
ded tire pressure is th e tire pressure specified
fo r th e tires mounted to th e ve hicle at th e fa c‐
to ry .
The tire and information ta ble con ta ins th e re c‐
ommended tire pressures fo r cold tires, th e max‐
imum permissible load and th e maximum per‐
missible ve hicle speed.
The tire pressure ta ble con ta ins th e re commen‐
ded tire pressures fo r cold tires under va ri ous
operating conditions, i.e. loading and/or speed
of th e ve hicle.
Increased ve hicle we ight due to optional
equipment: th e combined we ight of all st andard
and optional equipment av ailable fo r th e ve hicle, re ga rd less of whe th er it is actually ins ta lled on
th e ve hicle or not.
Rim: th e part of th e wheel on which th e tire is
ins ta lled.
GA WR (Gross Axle We ight Ra ting): th e GAWR
is th e maximum permissible axle load. The
actual load on an axle must ne ve r exc eed th e
gros s axle we ight ra ting. The gross axle we ight
ra ti ng
can be fo und on th e ve hicle identification
plate on th e B‑pillar on th e driver's side.
Speed ra ting: th e speed ra ting is pa rt of th e tire
identification. It specifies th e speed ra nge fo r
which a tire is appr ove d.
GV W (Gross Ve hicle We ight): th e gross ve hicle
we ight comprises th e we ight of th e ve hicle
including fuel, to ols, th e spare wheel, accesso‐
ri es ins ta lled, occupants, luggage and th e trailer
dr aw bar nose we ight, if applicable. The gros s
ve hicle we ight must not exc eed th e gross ve hicle
we ight ra ting GV WR as specified on th e ve hicle
identification plate on th e B‑pillar on th e driver's
side.
GV WR (Gross Ve hicle We ight Ra ting): th e
GV WR is th e maximum permitted gross we ight of th e fully laden ve hicle (weight of th e ve hicle
including all accessories, occupants, fuel, lug‐
ga ge and th e trailer dr aw bar nose we ight if appli‐
cable). The gros s ve hicle we ight ra ting is speci‐
fi ed on th e ve hicle identification plate on th e
B‑pillar on th e driver's side.
Maximum we ight of th e laden ve hicle: th e
maximum we ight is th e sum of th e curb we ight
of th e ve hicle, th e we ight of th e accesso ri es, th e
maximum load and th e we ight of optional equip‐
ment ins ta lled at th e fa ctor y.
Kilopascal (kPa): metric unit fo r tire pressu re .
6.9 kPa cor re sponds to 1 psi. Ano th er unit fo r
tire pressu re is bar . 10 0 ki lopascal (kPa) equals
1
bar.
Load index: in addition to th e load-bearing
index, th e load index may also be imprinted on
th e side wa ll of th e tire. This specifies th e load-
bearing capacity of th e tire more precisel y.
Curb we ight: th e we ight of a ve hicle with st and‐
ard equipment including th e maximum capacity
of fuel, oil and coolant. It also includes th e air
conditioning sy st em and optional equipment if Wheels and tires 431
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th ese are ins ta lled on th e ve hicle, but does not
include passengers or luggage.
Maximum tire load: th e maximum tire load is
th e maximum permissible we ight in kilog ra ms or
lbs fo r whi ch a tire is appr ove d.
Maximum permissible tire pressure: maxi‐
mum permissible tire pressure fo r one tire.
Maximum load on one tire: maximum load on
one tire. This is calculated by dividing th e maxi‐
mum axle load of one axle by two.
PSI (pounds per square in ch ): st andard unit of
measurement fo r tire pressu re .
Aspect ra tio: ra tio between tire height and tire
width in pe rc ent.
Ti re pressure: pressure inside th e tire applying
an outward fo rc e to eve ry square inch of th e tire.
The tire pressure is specified in pounds per
square inch (psi), in kilopascals (kPa) or in bar.
The tire pressure should only be cor re cted when
th e tires are cold.
Cold tire pressure: th e tires are cold when th e
ve hicle has been par ke d fo r at lea st 3 hou rs without direct sunlight on th e tires or th e ve hicle
has been driven fo r less th an 1 mile (1.6 km).
Ti re contact sur fa ce: th e part of th e tire th at
comes into con ta ct wi th th e ro ad.
Ti re bead: th e purpose of th e tire bead is to
ensure th at th e tire sits securely on th e wheel
ri m. There are se ve ra l wire cores in th e tire bead
to pr eve nt th e t ir
e from ch anging length on th e
wheel ri m.
Side wa ll: th e part of th e tire between th e tread
and th e tire bead.
We ight of optional equipment: th e combined
we ight of th e optional equipment we ighing more
th an th e re placed st andard parts and more th an
5 lbs (2.3 kg ). This optional equipment, such as
high-per fo rm ance brakes, le ve l control sy st em, a
ro of luggage ra ck or high-per fo rm ance bat te ri es,
is not included in th e curb we ight and th e we ight
of th e accessories.
TIN (Tire Identification Nu mber): a uni qu e
identification number which can be used by a
tire manufactu re r to identify tires, fo r ex ample,
in a product re call, and th us identify th e pur‐
ch asers. The TIN is made up of th e manufactur‐ er's identity code, tire size, tire type code and
th e manufacturing date.
Load-bearing index: th e load-bearing index is a
code th at con ta ins th e maximum load-bearing
capacity of a tire.
Tr action: traction is th e grip re sulting from fric‐
tion between th e tires and th e ro ad sur fa ce.
We ar indicator: nar row bars (tread we ar bars)
th at are distributed ove r th e tire con ta ct su rf ace.
If th e tire tread is le ve l with th e bars, th e we ar
limit of 1/ 16 in (1.6 mm) has been re ached.
Distribution of ve hicle occupants: distribution
of ve hicle occupants ov er designated seat posi‐
t ions in a ve hicle.
Maximum permissible pa yl oad we ight: nomi‐
nal load and luggage load plus 15 0 lb (68 kg )
multiplied by th e number of seats in th e ve hicle.432
Wheels and tires
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Changing a wheel
Note s on selecting, mounting and re placing
tires
Mercedes -A MG ve hicles: be sure to obser ve
th e no te s in th e Supplement. Otherwise, yo u
may not re cognize dangers.
Yo u can ask fo r information re ga rd ing permit te d
wheel/tire combinations at an authorized
Mercedes-Benz Center.
q
WA RNING Risk of accident due to incor‐
re ct dimensions of wheels and tires
If wheels and tires of th e wrong size are
ins ta lled, th e wheel brakes or wheel suspen‐
sion components may be damaged.
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