2005 BMW 645CI CONVERTIBLE Owners Manual

Wheels and tires
168
Wheels and tires
Tire inflation pressure
Information for your safety
It is not merely the tire's service life, but also
driving comfort and – to a great extent – driving
safety that depend on the condition of the tires
and the maintenance of the specified tire pres-
sure.
Checking tire inflation pressure
Only check tire inflation pressure 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. When tires are
warm, the tire inflation pressure increases.
Check the tire inflation pressure regularly
and correct it if necessary: at least every
two weeks and before beginning a longer trip. If
you fail to observe this precaution, you may be
driving on tires with incorrect tire pressures, a
condition that can not only compromise your
vehicle's stability, but also lead to tire damage
and the risk of an accident.<
After correcting the inflation pressure(s),
always reinitialize the Flat Tire Monitor,
refer to page84.<
Pressure specifications for factory-
installed tires
The tire inflation pressures with the ambient
temperature are visible on the door pillar with
the driver's door open.
Pressure specifications for other tire
sizes
The tables below provide all the correct inflation
pressures for the specified tire sizes at ambient
temperature.
For correct identification of the right tire
inflation pressure for your tires, observe
the specifications for the corresponding tire
size.<
Tire size
The specified pressures apply to tire sizes
approved by BMW and recommended tire
m a k e s ; y o u r B M W c en t e r w i ll b e g l a d t o p ro v id e
information.

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645Ci Coupe
645Ci Convertible
Tire sizePressure specifications in psi/kPa
All pressure specifications in
the table are indicated in psi/
kilopascal with cold tires –
cold = ambient temperature
245/50 R 17 99 H M+S
245/45 R 18 96 V M+S
245/45 R 18 96 V M+S all season29/200 32/220 33/230 39/270
Front: 245/45 R 18 96 W
Rear: 275/40 R 18 99 W29/200
––
32/22033/230
––
39/270
Front: 245/40 R 19 94 W
Rear: 275/35 R 19 96 W29/200
––
32/22033/230
––
39/270
Front: 245/35 R 20 91 Y
Rear: 275/30 R 20 93 Y29/200
––
32/22033/230
––
39/270
More details on the permitted load and weights can be found on page192.
Tire sizePressure specifications in psi/kPa
All pressure specifications in
the table are indicated in psi/
kilopascal with cold tires –
cold = ambient temperature
245/50 R 17 99 H M+S
245/45 R 18 96 V M+S
245/45 R 18 96 V M+S all season32/220 38/260 39/270 46/320
Front: 245/45 R 18 96 W
Rear: 275/40 R 18 99 W32/220
––
38/26039/270
––
46/320
Front: 245/40 R 19 94 W
Rear: 275/35 R 19 96 W32/220
––
38/26039/270
––
46/320
Front: 245/35 R 20 91 Y
Rear: 275/30 R 20 93 Y32/220
––
38/26039/270
––
46/320
More details on the permissible load and weights can be found on page192.

Wheels and tires
170
Tire identification marks
Knowledge of the labeling on the side of the tire
makes it easier to identify and choose the right
tires.
Tire size
Speed letter
T = up to 118 mph/190 km/h
H = up to 131 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
Tire Identification Number
Tires with DOT codes meet the guidelines of
the U.S. Department of Transport.
DOT code:
Tire age
The tire's date of manufacture is indicated on
the sidewall:
DOT ... 3604 indicates that a tire was manufac-
tured in week 36 of the year 2004.
BMW recommends replacing all tires at least
every 6 years, even if some tires may last for
10 years.
Uniform Tire Quality Grading
Quality grades can be found where applicable
on the tire sidewall between tread shoulder and
maximum section width. For example:
Tread wear 200 Traction AA
Temperature A
DOT Quality Grades
Tread wear
Traction AA A B C
Temperature A B C
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, 1γ, 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 e.g.
Nominal width
in mm
Aspect ratio in Ξ
Radial type
Rim diameter in inches
Load rating
not on ZR tires
Speed rating
before R on ZR tires
205/60 R 15 91 W
e.g.
Manufacturer code
for tire make
Tire size and tire design
Tire ageDOT xxxx xxx 3604

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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
You will recognize run-flat tires by a circular
symbol containing the letters RSC on the side
of the tire, refer to page172.
M+S
Winter and all-season tires.
These have better winter properties than sum-
mer tires.
Tire condition
Inspect your tires frequently for tread wear,
signs of damage and foreign objects lodged in
the tread, and check the tread depth.
Minimum tread depth
The tread depth should not drop below 0.12 in/
3 mm, although, for example, European legisla-
tion only specifies a minimum tread depth of
0.063 in/1.6 mm.
At tread depths below 0.12 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.
Winter tires noticeably loose their suitability for
winter use below a tread depth of 0.16 in/4 mm. New tires should be mounted in the interest of
safety.
Wear indicators at the tread-groove base, refer
to arrow, are distributed over the tire's circum-
ference and are marked on the side of the tire
with TWI – Tread Wear Indicator. If the indica-
tors are at the level of the profile, the legal per-
missible tread depth of 0.063 in/1.6 mm has
been reached.
Tire damage
Due to low-profile tires, please note that
wheels, tires and suspension parts are
more susceptible to road hazard and conse-
quential damages.
Unusual vibrations encountered during normal
vehicle operation can indicate tire failure or
some other vehicle defect. This can, for exam-
ple, be caused by driving over curbs. These
kinds of problems may also be signaled by other
changes in vehicle response, such as a strong
tendency to pull to the left or right.
In these cases reduce your speed immediately
and have the wheels and tires inspected imme-
diately. To do this, carefully drive to the next
BMW center or a specialized tire dealer which
works with personnel trained in accordance
with BMW specifications. Have the vehicle
towed to the workshop if necessary.
Tire damage can be extremely dangerous to
vehicle occupants and other road users.<
Unprofessional attempts by laymen to
service tires can lead to damage and acci-
dents. Have this work performed by skilled pro-
fessionals only. The technicians at your BMW
center will be glad to assist you with the
required professional knowledge and special-
ized equipment.<

Wheels and tires
172
Run-flat tires
You will recognize run-flat tires by the circular
symbol containing the letters RSC on the side-
wall.
Run-flat tires consist of self-contained tires and
special rims. The sidewall reinforcement
ensures that the tire retains some residual
safety in the event of pressure drop and driving
remains possible to a restricted degree.
New wheels and tires
Only have new wheels and tires mounted
by a BMW center or a specialized tire
dealer which works with personnel trained in
accordance with BMW specifications. If this
work is performed inexpertly, there is a danger
of damage and associated safety risks. Make
sure that the new wheels are balanced.<
Retreaded tires
BMW does not recommend the use of
retread tires, as otherwise driving safety
may be reduced. Possible variations in the
design and the age – which could be substan-
tial – of the carcasses can lead to more rapid
wear.<
The right wheels and tires
If you switch from summer to winter tires, or
vice versa, use run-flat tires, as in the event of a
flat tire there is no spare tire available. Your
BMW center will be glad to advise you.
For safety reasons, BMW recommends
that you do not have damaged run-flat
tires repaired; they should be replaced. wheel and tire combinations that BMW
has tested and approved for your particular
vehicle. Variations in factors such as manufac-
turing tolerances mean that even wheels and
tires with identical official size ratings could
actually have different dimensions than the
approved units – these differences could lead to
body contact, and with it the risk of severe acci-
dents. If non-approved wheels and tires are
used, BMW cannot evaluate their suitability,
and therefore cannot be held liable for driving
safety.<
You can find out the right wheel-tire combina-
tion from your BMW center.
The right wheel-and-tire combination is
another vital factor in ensuring reliable opera-
tion of various vehicle systems such as ABS
and DSC.
To maintain good handling and vehicle
response, use only tires of a single tread config-
uration from a single manufacturer. After a flat
tire, always remember to have the specified
wheel and tire combination remounted on the
vehicle as soon as possible.
Recommended tire brands
BMW tests certain tire brands for each tire size,
classifies them as road-safe and approves
them. Consult your BMW center for more infor-
mation. Observe any country-specific regula-
tions, e.g. on making a corresponding entry in
the vehicle documents.
The factory-mounted tires have been specially
selected to provide optimized performance
when installed on your vehicle; if properly cared
for, they will provide a combination of safety and
excellent ride comfort.
Special characteristics of winter tires
BMW recommends winter tires for use in cold
winter driving conditions. Although all-season
M+S tires provide better winter traction than
summer tires, they generally fail to provide the
same levels of cold-weather performance as
winter tires.

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Run-flat tires
If you switch from summer to winter tires, or
vice versa, use run-flat tires, refer to page172,
as in the event of a flat tire there is no spare tire
available. Your BMW center will be glad to
advise you.
Watch speed
Observe the permissible maximum speed
for the respective winter tires, as other-
wise tire damage and occur and cause acci-
dents.<
Storage
Always store wheels and tires in a cool, dry
place with as little exposure to light as possible.
Always protect tires against all contact with oil,
grease and fuels. Do not exceed the maximum
tire inflation pressure indicated on the side wall
of the tire.
Snow chains*
BMW only tests certain fine-link snow chains,
classifies them as road-safe and approves
them. Consult your BMW center for more infor-
mation. BMW recommends using these
approved snow chains. These snow chains are
approved exclusively for use in pairs on the rear
wheels with the tire size:
>245/50 R 17 Y
>245/45 R 18 Y
Observe the chain manufacturer's instructions
when mounting snow chains. Do not exceed a
vehicle speed of 30 mph/50 km/h with the
chains mounted.
Do not initialize the Flat Tire Monitor after
mounting snow chains.
When you are driving with snow chains, it can
be beneficial to switch off DTC briefly, refer to
page82.<

Under the hood
174
Under the hood
Never attempt to perform any service or
repair operations on your vehicle without
the required, professional technical training. If
you are unfamiliar with the specifications to be
observed, only have work carried out on your
vehicle by a BMW center or a workshop which
works with personnel trained in accordance
with BMW specifications. Otherwise there is a
danger of damage and associated safety risks if
this work is performed improperly.<
Hood
Releasing
Pull the lever located under the left side of the
instrument panel.
Opening
Press the release handle and open the hood.
Closing
Close the hood from a height of approx. 16 in/
40 cm with momentum. It must be clearly heard
to engage.
Make sure that the closing path of the
hood is clear, as otherwise injuries may
result.
If you see any signs that the hood is not com-
pletely closed while you are driving your vehicle,
you should stop at once and close it securely.<

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Engine compartment
1Filler neck for engine oil, refer to Topping off
engine oil
2Brake fluid reservoir, located beneath the
microfilter cover, refer to page177
3Dipstick for engine oil, refer to Checking oil
level
4Starting-aid terminal, refer to page186
5Washer fluid reservoir of the headlamp and
windshield cleaning systems, refer to
page61
6Expansion tank for coolant, refer to
page176
Engine oil
The engine oil consumption is dependent on
driving style and driving conditions.
Checking oil level
1.Park the vehicle on a level surface with the
engine warm, i.e. after an uninterrupted
drive of at least 6 miles/10 km.
2.Switch off the engine.3.After approx. 5 minutes, pull the dipstick3
out and wipe it off with a clean lint-free
cloth, paper towel, or similar material.
4.Carefully push the dipstick all the way into
the guide tube and pull it out again.
The oil should extend to between the two
marks on the dipstick.
The oil quantity between the centers of the two
marks on the dipstick, refer to arrows, is approx.
1.6 US quarts/1.5 liters.
Do not fill beyond the upper mark on the
dipstick. Excess oil can damage the
engine.<