MERCEDES-BENZ S CLASS 2018 Owners Manual
Page 431 of 562
Preceding letter 1 :R
Wi th out: passenger ve hicle tires according to
European manufactu ri ng st andards.R
"P": passenger ve hicle tires according to US
manufacturing st andards.R
"LT": light truck tires according to US manu‐
fa cturing st andards.R
"T": compact emer ge ncy spa re wheels with
high tire pressure th at are on ly designe d fo r
te mp orary use in an emer ge ncy.
Aspect ra tio 3 :
Ra tio between tire height and tire width in per‐
cent (ti re height divided by tire width).
Tire code 4 (ti re type):R
"R" ra dial tireR
"D": bias ply tire R
"B": bias belted tires R
"ZR": ra dial tire with a maximum speed abo ve
14 9 mp h (240 km/h) (optional) Rim diame te r 5 :
The diam et er of th e bead seat (not th e diame te r
of th e ri m fl ange). The ri m diame te r is specified
in inches (in).
Load-bearing index 6 :
Numerical code th at specifies th e maximum
load-bearing capacity of a tire (e.g. "91" cor re ‐
sponds to 13 56 lbs (6 15 kg )).
The load-bearing capacity of th e tire must be at
least half th e permissible axle load of yo ur ve hi‐
cle. Do not ove rl oad th e tires by exc eeding th e
specified load limit.
See also: R
Maximum permissible load on th e Ti re and
Loading In fo rm ation placard ( →
page 420)R
Maximum tire load ( →
page 427)R
Load ind ex
Speed ra ting 7 :
Specifies th e appr ove d maximum speed of th e
tire.
Page 432 of 562
Inde xS peed ra ting
ZR...Y 1
up to 18 6 mp h (3 00 km/h)
ZR...(..Y) 1
ove r 18 6 mp h (3 00 km/h)
ZR 1
ove r 14 9 mp h (240 km/h)R
Specifying th e speed ra ting as th e "ZR" index
in tire code 4 is optional fo r tires up to
18 6 mp h (3 00 km/h).R
If yo ur tire co de 4 includes "ZR" and th ere
is no speed ra ting 7 , fi nd out what th e max‐
imum speed is from th e tire manufacturer.R
If load-bearing index 6 and speed ra ting 7
are in brac ke ts, th e maximum speed ra ting of
yo ur tire is abo ve 18 6 mp h (300 km/h). To
fi nd out th e maximum speed, ask th e tire
manufacturer. All-weather tires and winter tires
Inde xS peed ra ting
Q M+S 2
up to 10 0 mp h (160 km/h)
T M+S 2
up to 11 8 mp h (1 90 km/h)
H M+S 2
up to 13 0 mp h (2 10 km/h)
V M+S 2
up to 14 9 mp h (240 km/h)
Wi nter tires bear th e M snowflake symbol
and fulfill th e requ irements of th e Ru bber Manu‐
fa cturers Association (RMA) and th e Ru bber
Association of Canada (RAC) re ga rd ing th e tire
traction on sno w.
Load index 8 : R
No specification given: st andard load (SL)
tire R
"XL" or "Extra Load": ex tra load tire or re in‐
fo rc ed tire R
"Light Load": light load tire R
"C", "D", "E": a load ra nge th at depends on
th e maximum load th at th e tire can car ry at a
cer ta in pressure
Definition of term s fo r tires and loading
Ti re stru ctu re and ch aracteristics: describes
th e number of la ye rs or th e number of ru bber-
coated belts in th e tire con ta ct su rf ace and th e
tire wa ll. These are made of st eel, ny lon, poly‐
es te r and ot her materials.
Bar: metric unit fo r tire pressu re .
14 .5038 pounds per square inch (psi) and
10 0 kilopascal (kPa) is th e equivalent of one bar.
DOT (Department of Tr anspo rt ation): DO T-
mar ke d tires fulfill th e requ irements of th e
US Department of Tr anspor ta tio n.
Av erage we ight of th e ve hicle occupants: th e
number of ve hicle occupants fo r whi ch th e ve hi‐
cle is designed, multiplied by 15 0 lb (68 kg ).
1
"ZR" st ated in th e tire code.2
Or "M+S M " fo r winter tires430
Wheels and tires
Page 433 of 562
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
Page 434 of 562
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
Page 435 of 562
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.