Page 67 of 172
66n
Tire Pressure Warning (RDW)
Check tire pressure on a regular
basis and correct it if you need to.
Refer to page 24.
Do not carry out any system activation
while driving with snow chains or while
driving on curves. Malfunction warnings
and undetected losses are possible
while driving under these types of
conditions.
In certain circumstances, there could
be a delayed detection of any loss in in-
flation pressure while driving on snow-
covered or slippery road surfaces.
A sporty driving style can also cause
delayed RDW alerts (e. g. slippage in
the drive wheels, high lateral accelera-
tion).<
System interferenceThe red indicator lamp in the instrument
cluster will stay on for as long as there
is a malfunction.
The indicator lamp will come on if the
system malfunctions.
Please contact your BMW center for
additional information.
Page 102 of 172

101n
IndexDataTechnologyRepairsCar careControlsOverview
Wheel and tire combinations The right choice Use only BMW-approved tires with
emergency driving characteristics.
Refer to page 103.
Due to the maximum speeds this vehi-
cle can reach, the use of specific brands
and sizes is mandatory. Consult any
BMW center for details. Comply with
local/national regulations.
The correct wheel/tire combinaton
affects different sytems, such as
ABS, ATC, DSC and RDW. The function
of these systems is impaired if improper
wheel/tire combinations are used.
For this reason, use only tires made by
the same manufacturer that have the
same tread configuration and possess
emergency driving characteristics. And
after a flat tire, for instance, restore the
approved wheel-tire combination as
soon as possible.<
Codes on tires and wheels The tire codes will aid you in selecting
the correct tire.
Codes on radial tires:
The speed rating indicates the approved
maximum speed for the tire.
Summer tires:
S = up to 112 mph (180 km/h)
T = up to 118 mph (190 km/h)
H = up to 130 mph (210 km/h)
V = up to 150 mph (240 km/h)
W = up to 167 mph (270 km/h)
Y = up to 186 mph (300 km/h)
ZR = over 150 mph (240 km/h) For example:
Nominal width
in mm
Aspect ratio in X
Radial tire code
Rim diameter in inches
Load rating
(not on ZR tires)
Speed rating
(before R on ZR tires)
245/45 R 18 96 W
Winter tires:
Q M+S = up to 100 mph (160 km/h)
T M+S = up to 118 mph (190 km/h)
H M+S = up to 130 mph (210 km/h)
Codes stamped on light-alloy wheels:
Protect tire valves from dirt by using
screw-on valve stem caps. Dirt in the
valves frequently leads to slow leaks.
Tires with emergency driving character-
istics also possess an additional identi-
fication mark that varies by manufac-
turer, e. g.:
Bridgestone RFT
Dunlop DSST
Goodyear EMT
Michelin ZP For example:
Rim width
in inches
Code letter for
flange type
Symbol for full-drop
center rim
Rim diameter in inches
Hump on the 2 rim shoulders
8 x 18 H 2
J
Page 104 of 172

103n
IndexDataTechnologyRepairsCar careControlsOverview
Approved wheel and tire specifications Comply with the specifications for tires
and wheels in the vehicle's documents.
If sizes not approved by the manufac-
turer are mounted, an entry in the vehi-
cle's documents may be necessary. Tire specifications Light-alloy wheel
BMW Z8
Summer tires
Front: 245/45 R 18 96 W 8Jx18 EH2
Rear: 275/40 R 18 99 W 9Jx18 EH2
Winter tires
245/45 R 18 96 H M+S 8Jx18 EH2
Snow chains
*
It is impossible to install snow chains
when using summer tires 275/40 R 18
99 W.
Do not activate the RDW system
while using snow chains.
Malfunction warnings and undetected
losses in pressure are possible when
driving with snow chains.
For further information, refer to
page 65.<
The use of rims and wheel bolts
that do not meet the specifications
of the original factory-installed equip-
ment will affect the safe operation of
your vehicle and may cause an accident
and personal injury.
Never mix tires of different design, such
as steel-belted radials with radial bias
belted or bias-ply tires, etc. Mixing tire
types will adversely affect roadholding
and can lead to loss of vehicle control.<