2007 BMW Z4 3.0SI ROADSTER page 97

Wheels and tires
84
Wheels and tires
Tire inflation pressure
Information for your safety
It is not merely the tire's service life, but also
driving safety and driving comfort that largely
depend on the condition of the tires and the
maintenance of the specified tire pressure.
Check tire inflation pressures regularly
and correct them if necessary: at least
every two weeks and before every extended
journey. If you fail to observe this precaution
you may be driving on tires with incorrect tire
pressures, a condition that can not only com-
promise your vehicle's driving stability, but also
lead to tire damage and the risk of an accident.
Do not drive with deflated, i.e. flat tires, except
when using Run-Flat Tires. A flat tire will seri-
ously impair your vehicle's handling and braking
response. Attempts to drive on a flat tire can
lead to loss of control over the vehicle.<
Checking pressure
Check the tire inflation pressures only when the
tires are cold. This means after a maximum of
1.25 miles/2 km driving or when the vehicle has
been parked for at least 2 hours. Warm tires
have higher inflation pressures.
Inflation pressure specifications
The specified inflation pressures for your stan-
dard tires are provided on the placard on the
B-pillar and are visible when the driver's door is
open.After the tire inflation pressure is cor-
rected, initialize the Flat Tire Monitor
*,
refer to page53, or reset the Tire Pressure
Monitor
*, refer to page54.<
The following tire inflation pressure tables show
the inflation pressures for the specified tire
sizes at ambient temperature.
The inflation pressures in the table apply
to BMW-approved tire sizes and recom-
mended tire brands. Your BMW center will be
glad to supply this information.<
To determine the correct tire inflation pressure
for your tires, refer to the following tables.
Tire size
The inflation pressures in the table apply to
BMW-approved tire sizes and recommended
tire brands. Your BMW center will be glad to
supply this information.

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Z4 Roadster 3.0i
Z4 Roadster 3.0si
Tire sizePressure specifications in psi/kPa
All pressure specifications in the table are
indicated in psi/kilopascal with cold tires,
cold = ambient temperature
225/50 R 16 92 V
225/45 R 17 91 W
205/55 R 16 91 H M+S
225/50 R 16 92 H M+S
225/45 R 17 91 H/V M+S32/220 35/240
Front: 225/45 R 17 91W
Rear: 255/40 R 17 94 W32/220
––
35/240
Front: 225/40 R 18 88 W
Rear: 255/35 R 18 90 W32/220
––
35/240
You will find more information about permissible loads and weights on page113.
Tire sizePressure specifications in psi/kPa
All pressure specifications in the table are
indicated in psi/kilopascal with cold tires,
cold = ambient temperature
225/45 R 17 91 W
225/45 R 17 91 H/V M+S33/230 38/260
Front: 225/45 R 17 91W
Rear: 255/40 R 17 94 W33/230
––
38/260
Front: 225/40 R 18 88 W
Rear: 255/35 R 18 90 W33/230
––
38/260
You will find more information about permissible loads and weights on page113.

Wheels and tires
86
Z4 Coupe 3.0si
Tire coding
Understanding the lettering on the tire sidewall
makes it easier to identify and choose the cor-
rect tires.
Tire size
Speed code letter
Q = up to 100mph or 160km/h
T = up to 118mph or 190km/h
H = up to 131mph or 210km/h
V = up to 150mph or 240km/h
W = up to 167mph or 270km/h
Y = up to 186mph or 300km/h
Tire Identification Number
Tires with DOT codes meet the guidelines of
the U.S. Department of Transportation.DOT code:
Tire age
The date on which the tire was manufactured is
indicated by the code on the sidewall:
DOT … 5005 indicates that the tire was manu-
factured in week 50 of the year 2005.
BMW recommends the replacement of all tires
every 6 years at the latest, even if a tire usage of
10 years is possible.
Uniform Tire Quality Grading
Quality grades can be found where applicable
on the tire sidewall between tread shoulder and
maximum section width. For example:
Treadwear 200 Traction AA
Temperature A
DOT Quality Grades
Tread wear
Traction AA A B C
Temperature A B C
Tire sizePressure specifications in psi/kPa
All pressure specifications in the table are
indicated in psi/kilopascal with cold tires,
cold = ambient temperature
225/45 R 17 91 W
225/45 R 17 91 H/V M+S33/230 39/270
Front: 225/45 R 17 91W
Rear: 255/40 R 17 94 W33/230
––
39/270
Front: 225/40 R 18 88 W
Rear: 255/35 R 18 90 W33/230
––
39/270
You will find more information about permissible loads and weights on page113.
e.g.
Nominal width in mm
Aspect ratio in Ξ
Radial belt construction
Rim diameter in inches
Load rating,
not on ZR tires
Speed code letter, in
front of the R on ZR tires225/50 R1692 V
e.g.
Manufacturer's code
for tire make
Tire size and
tire design
Tire ageDOT xxxx xxx 5005

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All passenger car tires must conform to
Federal Safety Requirements in addition
to these grades.<
Tread wear
The tread wear grade is a comparative rating
based on the wear rate of the tire when tested
under controlled conditions on a specified gov-
ernment test course.
For example, a tire graded 150 would wear one
and one-half, 1 γ, times as well on the govern-
ment course as a tire graded 100. The relative
performance of tires depends upon the actual
conditions of their use, however, and may
depart significantly from the norm due to varia-
tions in driving habits, service practices and dif-
ferences in road characteristics and climate.
Traction
The traction grades, from highest to lowest, are
AA, A, B and C.
Those grades represent the tire's ability to stop
on wet pavement as measured under controlled
conditions on specified government test sur-
faces of asphalt and concrete. A tire marked C
may have poor traction performance.
The traction grade assigned to this tire is
based on straight-ahead braking traction
tests, and does not include acceleration, cor-
nering, hydroplaning, or peak traction charac-
teristics.<
Temperature
The temperature grades are A, the highest, B
and C, representing the tire’s resistance to the
generation of heat and its ability to dissipate
heat when tested under controlled conditions
on a specified indoor laboratory test wheel.
Sustained high temperature can cause the
material of the tire to degenerate and reduce
tire life, and excessive temperature can lead to
sudden tire failure. The grade C corresponds to
a level of performance which all passenger car
tires must meet under the Federal Motor Vehi-
cle Safety Standard No. 109. Grades B and A
represent higher levels of performance on the
laboratory test wheel than the minimum
required by law.The temperature grade for this tire is
established for a tire that is properly
inflated and not overloaded. Excessive speed,
underinflation, or excessive loading, either sep-
arately or in combination, can cause heat
buildup and possible tire failure.<
RSC: Run-Flat Tires
Run-Flat tires are labeled on the sidewall with a
circular symbol containing the letters RSC.
Refer to page88.
M+S
Winter and all-season tires.
These have better winter performance proper-
ties than summer tires.
Tire condition
Inspect your tires frequently for tread wear,
signs of damage and for foreign objects lodged
in the tread. Check the tread depth.
Minimum tread depth
The tread depth should not drop below 1/8 in/
3 mm, although, for example, European legisla-
tion only specifies a minimum tread depth of
1/16 in/1.6 mm. At tread depths below 1/8 in/
3 mm there is an increased risk of high-speed
hydroplaning, even when only small amounts of
water are present on the road surface.
When winter tires wear down past a tread depth
of 1/6 in/4 mm, they become perceptibly less
suitable for winter conditions. In the interest of
safety, new tires should be installed.
Wear indicators in the base of the tread groove
are distributed around the tire's circumference;

Wheels and tires
88 the letters TWI, for Tread Wear Indicator, on the
tire's sidewalls identify tires that incorporate
these wear indicators. Once the tire tread has
worn down to the wear indicators, the tire has
worn to a depth of 1/16 in/1.6 mm.
Wheel/tire damage
Due to low-profile tires, please note that
wheels, tires and suspension parts are
more susceptible to road hazards and conse-
quential damages.<
Unusual vibrations encountered during normal
vehicle operation can indicate tire failure or
some other vehicle malfunction. This can, for
example, be caused by driving over curbs. The
same applies to any other abnormal road
behavior, such as pulling severely to the right or
left.
In these cases, reduce speed immedi-
ately and have wheels and tires thor-
oughly checked. To do so, drive carefully to the
nearest BMW center or tire shop that works
according to BMW repair procedures with cor-
respondingly trained personnel. If necessary,
have the vehicle towed there.
Tire damage can be extremely dangerous for
vehicle occupants and other road users.<
Tire age
For various reasons, such as the development
of brittleness, BMW recommends tire replace-
ment after no more than 6 years, regardless of
the actual wear of the tires.
The date on which the tire was manufactured is
indicated by the code on the sidewall:
DOT … 5005 indicates that the tire was manu-
factured in week 50 of the year 2005.
Run-Flat Tires
The symbol identifying Run-Flat Tires is a circle
with the letters RSC on the sidewall.
Run-Flat Tires comprise a conditionally self-
supporting tire and a special rim. The reinforce-
ment in the sidewalls ensures that the tire can
continue to be used subject to certain restric-
tions, even if depressurized.
To continue driving with a damaged tire:
>If the vehicle is equipped with the Flat Tire
Monitor, refer to Flat tire warning on
page53.
>If the vehicle is equipped with the Tire Pres-
sure Monitor, refer to Warning of low tire
inflation pressure on page54.
Wheel and tire replacement
Have new wheels and tires installed only
by your BMW center or tire shop that
works according to BMW repair procedures
with correspondingly trained personnel. Work
that is improperly carried out could result in
consequential damage and pose safety haz-
ards. Make sure that the new wheels are bal-
anced.<
Retreaded tires
BMW advises against using retreaded
tires, since driving safety may be
impaired. The causes for this include potentially
different tire casing structures and often wide
variations in tire age, which can result in a lim-
ited service life.<

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Correct wheels and tires
BMW recommends using only wheels
and tires that have been approved by
BMW for your particular vehicle model, other-
wise body contact and serious accidents can
result despite the use of the same nominal size,
e.g. due to manufacturing tolerances. If non-
approved wheels and tires are used, BMW can-
not evaluate their suitability, and therefore can-
not be held liable for driving safety.<
You can inquire about the correct wheel/tire
combination at your BMW center.
The correct combination of wheels and tires is
also necessary to ensure reliable operation of
various vehicle systems such as ABS and DSC.
To maintain good handling and vehicle
response, only use tires of a single brand and
tread configuration. After a tire has been dam-
aged, for instance, mount the original wheel and
tire combination again as soon as possible.
Wheels with electronics for the Tire
Pressure Monitor TPM
When mounting new tires or changing from
summer to winter tires or vice versa, only use
wheels with TPMS electronics; otherwise the
Tire Pressure Monitor would not be able to
detect a flat tire, refer to page54. Your BMW
center will be glad to provide you with more
information.
Recommended tire brands
Certain makes of tire are recommended by
BMW for each tire size. They are marked with a
clearly visible BMW designation on the sidewall
of the tire.When properly used, these tires meet the high-
est standards in terms of safety and handling
characteristics.
Run-Flat Tires
When mounting new tires or changing over
from summer to winter tires and vice versa,
mount Run-Flat Tires for your own safety. In the
event of a flat, moreover, no spare wheel is
available. Your BMW BMW center will be glad to
provide you with more information.
For safety reasons, BMW recommends
that damaged Run-Flat Tires be replaced
rather than repaired.<
Special characteristics of winter tires
BMW recommends the use of winter tires for
operation under winter road conditions. While
all-season tires with M+S designation provide
better winter traction than summer tires, they
generally do not achieve the full performance of
winter tires.
Pay attention to speed
Always comply with the speed limit for the
winter tires mounted on your car; failure
to do so could result in tire damage and acci-
dents.<
If the car is capable of speeds higher than that
permitted for the winter tires, a label stating the
maximum permitted speed for the mounted
tires must be displayed in your field of view.
Specialist tire dealers and your BMW center
can supply these labels.
Storage
Store tires in a cool, dry place, protecting them
against light whenever possible. Protect the
tires from contact with oil, grease and fuel. Do
not exceed the maximum tire inflation pressure
indicated on the sidewall of the tire.
Swapping wheels between the axles
BMW advises against moving the front wheels
to the rear wheel positions and vice versa, as
this may impair vehicle handling characteristics.

Wheels and tires
90
Snow chains*
Only certain fine-link snow chains have been
tested by BMW, classified as safe for use and
recommended. Consult your BMW center for
more information. Attach snow chains in pairs
and only to the rear wheels.
Observe the manufacturer's instructions when
mounting snow chains. Do not exceed a speed
of 30 mph/50 km/h when using snow chains.
You are not permitted to mount snow chains to
tires of the following sizes:
>255/40 R 17
>255/35 R 18
Do not initialize the Flat Tire Monitor if
snow chains are mounted
*, as this may
cause the instrument to issue an incorrect read-
ing.
When driving with snow chains, you may find it
helpful to activate DTC temporarily, refer to
page52.<

Under the hood
92
Important parts in the engine compartment
1Washer fluid reservoir for headlamp clean-
ing system and window washer system,
refer to page46
2Filler neck for engine oil, refer to Adding
engine oil3Jump-starting connection, refer to
page104
4Reservoir for brake fluid, refer to page95
5Body ground, negative terminal, refer to
page105
6Expansion tank for coolant, refer to page94
Engine oil
Oil consumption is directly influenced by your
driving style and vehicle operating conditions.
Warning lamp
Engine oil pressure
The warning lamp lights up in red:
The engine oil pressure is too low.
Stop the vehicle immediately and
switch off the engine. Check the engine oil level
and top up if necessary. If the oil level is correct,
please contact your nearest BMW center or a
workshop that works according to BMW repair
procedures with correspondingly trained per-
sonnel.Do not continue driving, otherwise the
engine could sustain serious damage
from inadequate lubrication.<
Engine oil level
The warning lamp lights up in yellow
while you are driving. In addition, a sig-
nal sounds and "+1.0" appears in the
instrument cluster, refer to page93.
The oil level is at the absolute minimum; refill as
soon as possible. Do not drive more than
125 miles/200 km before refilling.
The warning lamp comes on in yellow
after the engine is switched off. A signal
also sounds.