width Alfa Romeo 166 2007 Owner handbook (in English)

146
A - Normal pressure: tread uniform-
ly worn.
A correct pressure will ensure a longer
life for your tyre and improve perfor-
mance as the tread will then be working
along the entire width of the tread and
wear will be more uniform.
These conditions also lead to:
– better road holding of the vehicle
– easier and more precise steering
– reduced fuel consumption due to a
lower resistance against the rolling of the
tyre.
B - Insufficient pressure: tread
worn more along the edge.
Low tyre pressure will cause irregular
wearing of the tread (greater along the
sides) and cause the tyre to overheat
which could lead to parts of the tyre
breaking off and cause damage to the
shell of the tyre itself.
This type of damage could lead to sud-
den loss of pressure or cause the tyre to
burst.C - Excessive pressure: tread worn
more towards the centre.
Overinflating the tyres leads to:
– irregular wearing of the tread, con-
centrated more towards the centre of the
tread
– a reduction in the level of comfort
– a greater vulnerability of the tyre to
knocks
IMPORTANT When the vehicle is be-
ing used the pressure increases naturally.
In exceptional cases when checking tyre
pressure when hot, do not reduce the
pressure.Wheel balancing
Each wheel together with its tyre is bal-
anced, both satirically and dynamically, in
the factory. When the tyres are replaced
the wheels must be rebalanced to prevent
vehicle instability, wearing of the compo-
nents of the steering system and irregular
tyre wear.
When balancing wheels
made of light alloy only
original Alfa Romeo
counterweights should be used.

248
CORRECT TYRE READING
Below are the instructions necessary to know the meaning of
the code stamped on the tyre.
The code may be like one of the examples given below.
225= Nominal width (distance in mm between the sides).
45= Percentage height/width ratio.
R= Radial tyre.
ZR= Radial tyre with speed above 240 kph.
17= Rim diameter in inches.
91= Load (capacity) index, e.g. 91 = 600 kg. Not present in
ZR tyres.
Y, Z= Maximum speed index. In ZR tyres the speed index Z is
before the R.Load index (capacity)
60= 250 kg84= 500 kg
61= 257 kg85= 515 kg
62= 265 kg86= 530 kg
63= 272 kg87= 545 kg
64= 280 kg88= 560 kg
65= 290 kg89= 580 kg
66= 300 kg90= 600 kg
67= 307 kg91= 615 kg
68= 315 kg92= 630 kg
69= 325 kg93= 650 kg
70= 335 kg94= 670 kg
71= 345 kg95= 690 kg
72= 355 kg96= 710 kg
73= 365 kg97= 730 kg
74= 375 kg98= 750 kg
75= 387 kg99= 775 kg
76= 400 kg100= 800 kg
77= 412 kg101= 825 kg
78= 425 kg102= 850 kg
79= 437 kg103= 875 kg
80
= 450 kg104= 900 kg
81= 462 kg105= 925 kg
82= 475 kg106= 950 kg
83= 487 kg Example:
225/45 R 17 91 Y
or
225/45 ZR 17

249
fig. 7 Maximum speed index
Q= up to 160 kph.
R= up to 170 kph.
S= up to 180 kph.
T= up to 190 kph.
U= up to 200 kph.
H= up to 210 kph.
V= over 210 kph.
ZR= over 240 kph.
W= up to 270 kph.
Y= up to 300 kph.
Maximum speed index for snow tyres
Q M+S= up to 160 kph.
T M+S= up to 190 kph.
H M+S= up to 210 kph.Example:
6.5J x 16”
UNDERSTANDING RIM MARKING
The following are the necessary indications to understand the
meaning of the markings on the rim, as shown in fig. 7.
6.5= Rim width in inches (1)
J= Rim drop centre outline (side projection where the tyre bead
rests) (2)
16”= Rim nominal diameter in inches (corresponds to diameter
of the tyre to be mounted) (3= Ø)
002STZm