106n
Antilock Brake System (ABS)The concept ABS enhances active safety by helping
to prevent the wheels from locking un-
der braking. This is because locked
wheels are dangerous. When the front
wheels slide, the driver loses steering
control over the vehicle. Traction loss at
the rear wheels can cause the rear end
to break into an uncontrolled skid.
ABS is designed to meet two essential
requirements during every brake appli-
cation:
>To help provide vehicle stability
>To help maintain steering control and
maneuverability Ð on all types of road
surfaces (asphalt, concrete, mud, wet,
snow, ice).
The system can achieve the shortest
braking distances possible under most
conditions (on straight-aways and in
curves, on asphalt, ice, wet road sur-
faces, etc.).
Braking with ABSThe system becomes operative once
the vehicle exceeds a speed of approx.
6 mph (10 km/h). Below approx. 3 mph
(6 km/h), it is once again deactivated.
This means that the wheels can lock in
the final phase of a panic stop Ð a factor
of no significance in actual use.
If you are in a situation that requires full
braking, you will exploit the full benefits
of the ABS system if you apply maxi-
mum brake pressure ("panic stop").
Since the vehicle maintains steering re-
sponsiveness, you can avoid possible
obstacles with a minimum of steering
effort, despite the full brake application.
The ABS system closed-loop control
circuit cycles in fractions of a second.
A pulsation at the brake pedal indicates
to the driver that ABS is active, that is,
that the vehicle is within its maximum
braking range. In addition, a pulsation Ð
a result of the control function cycles Ð
indicates to the driver that vehicle
speed should be reduced to adapt to
road surface conditions when there is
reduced traction and grip between tires
and road surface (slippery road sur-
face).
On road surfaces that have a loose sur-
face layer on a firm base with good
traction (on gravel or snow, for exam-ple), or when snow chains are mounted,
braking distances may be longer than
with locked wheels. However, ABS
continues to provide enhanced vehicle
stability and steering response under
these conditions.
Information for your safetyNot even ABS can suspend the laws of
physics. ABS cannot prevent the con-
sequences of brake applications with
inadequate clearances for safety be-
tween vehicles, when exceeding the
speed limit in curves, or the risks in-
volved when aquaplaning occurs. Re-
sponsibility for these types of situations
remains in the hands (and at the feet) of
the driver. You should never allow the
added safety of ABS to lull you into a
false sense of security, or mislead you
into taking increased risks that could af-
fect your own safety and that of others.
Do not make any modifications to
the ABS system.
Service procedures on ABS are to be
performed by authorized technicians
only.<
110n
Winter operationThe onset of winter is often accompa-
nied by rapid changes in weather.
Adaptations in driving style should be
accompanied by preparations on the
vehicle itself to ensure that your
progress through the winter remains
safe and trouble-free.CoolantBe sure that the coolant mixture con-
tains the year-round ratio of 50:50
water and extended-duty antifreeze/
corrosion protection. This mixture pro-
vides protection against freezing down
to approx. Ð 34 7 (Ð 37 6). Replace
the coolant every four years.LocksBMW door lock deicer can be used to
free them if frozen. This deicer also
contains lubricant.
After its use, treatment with BMW lock
barrel grease is recommended.Rubber seals and components To prevent the weather-stripping from
freezing, apply a spray-on rubber treat-
ment or silicone spray to the door, hood
and luggage compartment lid seals.
A full range of car care products is
available from your BMW center.<
Snow chains BMW snow chains
* can be mounted on
both summer and winter tires. Mount
them in pairs on the rear wheels only
and comply with the manufacturer's
safety precautions. Do not exceed a
maximum speed of 30 mph (50 km/h).
For best performance, deactivate the
DSC when snow chains are mounted.
Refer to page 79.
Starting offWhen starting from a full stop in deep
snow or for "rocking" the vehicle to free
it, we recommend that you deactivate
the DSC system. Refer to page 79.Driving on low-traction road
surfacesUse smooth, gentle pressure to control
the accelerator pedal. Avoid excessive
engine speeds and shift to the next
higher gear at an early point. On down-
grades or slopes, shift down to the next
lower gear at an early point. Maintain an
adequate distance between yourself
and the car ahead.
BrakesWinter road conditions substantially re-
duce the traction available between the
tires and the road surface. Remember
that braking distances will be signifi-
cantly longer as a result.
ABS is intended to prevent the wheels
from locking during brake applications,
thus helping to maintain vehicle stability
and steering response.
If the ABS does not respond in a critical
braking situation and the wheels lock:
Reduce the pressure on the brake pedal
until the wheels just start to roll again
while still maintaining enough force to
continue braking.
Following that, increase pedal pressure
again. Reduce the pressure as the
wheels lock, then reapply pressure.
Repeat this procedure. This type of
staggered braking will reduce the brak-
ing distance, and the vehicle still re-
mains responsive to steering. It allows
you to steer around hazards once you
have reduced the pressure on the brake
pedal.
116n
Wheel and tire combinations The right choice Use only BMW-approved tires. Refer to
page 118.
Due to the high speeds this vehicle can
reach, the use of specific brands, spec-
ifications and sizes is mandatory. Con-
sult any BMW center for details. Com-
ply with local/national regulations.
The correct wheel-tire combina-
tion affects different systems such
as ABS, ATC and DSC. The function of
these systems is impaired if improper
wheel-tire combinations are used.
For this reason, use only tires of the
same brand and tread pattern. In the
event of a flat tire, for example, remount
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.
The 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 = above 167 mph (270 km/h)
ZR = above 150 mph (240 km/h) Example:
Nominal width
in mm
Aspect ratio in %
Radial tire ID code
Rim diameter in inches
Load rating
(not on ZR tires)
Speed rating
(before R on ZR tires)
205/60 R
1591W
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 valve from dirt by using
screw-on valve stem caps. Dirt in the
valves frequently leads to slow leaks. 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
7 x 15 H 2
J