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137n
Catalytic converter Antilock Brake System (ABS)
Be sure to comply with the
instructions above to prevent
unburned fuel from reaching the cata-
lytic converter. Otherwise, the catalytic
converter could respond by over-
heating, leading to serious damage.
Extreme temperatures occur at the
catalytic converter on this and every
catalyst-equipped vehicle. Heat shields
are installed adjacent to some sections
of the exhaust system. Never remove
these shields; do not apply under-
coating to their surfaces. When driving,
standing at idle, and parking the
vehicle, take care to avoid contact
between the exhaust system and flam-
mable materials (grass, hay, leaves,
etc.). Such contact could lead to a fire,
resulting in serious personal injury and
property damage.<
The concept ABS enhances active safety by helping
to prevent the wheels from locking
under 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.
With ABS, you will achieve the shortest-
possible braking distances under all
given conditions (braking while driving
straight ahead or in curves, different
road surfaces).
ABS is designed to meet two essential
requirements during every brake appli-
cation:
>To help provide vehicle stability.
>To help retain steering and maneu-
vering capability on all types of road
surfaces (asphalt, cement, dirt, wet
surfaces, snow and ice).
Braking with ABS The system becomes operative once
the vehicle exceeds a speed of approx.
6 mph (10 km/h). The ABS is inactive
again whenever the vehicle's speed
drops back below approx. 4 mph
(6 km/h).
To shorten the braking distance — espe-
cially on steep, poor road surfaces when
driving slowly straight ahead — the
system allows one or both front wheels
to lock for a short time. Nevertheless,
the vehicle still retains steering
response since this "poor road logic" is
deactivated again automatically as you
steer.
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
responsiveness, you can avoid possible
obstacles with a minimum of steering
effort, despite the full brake application.
The ABS system's closed-loop control
circuit cycles in fractions of a second.
A pulsation at the brake pedal, together
with the sounds associated with the
hydraulic controls, tells you that the
brake system is within its maximum
limit range and reminds you that you
148n
Wheel and tire combinationsThe right choice
Use only wheels and tires
approved by BMW for the corre-
sponding vehicle model, as otherwise
the tires may make contact with the
body as the result of tolerances despite
the same nominal size being used,
resulting in serious accidents. If non-
approved wheels and tires are used,
BMW cannot evaluate their suitability,
and therefore cannot be held liable for
driving safety.<
For wheel and tire specifications
approved by BMW, refer to page 150.
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 on the
vehicle and, for example, restore the
approved wheel-tire combination
following a flat tire as soon as
possible.<
Codes on the tires and wheels The code on tires has the following
meaning.
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) Example:
Nominal width
in mm
Aspect ratio in X
Belt rating code for
radial tires
Rim diameter in inches
Load rating
(not on ZR tires)
Speed rating
(before R on ZR tires)
235/65 R 17 104 H
All-season, all-terrain and 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 on light-alloy wheels:
Protect valve stems and valves from dirt
using screw-on valve stem caps. Dirt in
the valves frequently leads to slow
leaks. Storage Store tires in a cool, dry place,
protecting them against light when-
ever possible. Protect the tires against
contact with oil, grease and fuel. Example:
Rim width
in inches
Code letter for
flange type
Symbol for full-drop
center rim
Rim diameter in inches
Special extended hump
on the 2 rim shoulders
7.5 x 17 SEH 2
J
