BMW 2006 X5 Owner's Manual page 147

Wheel/tire condition
Tire tread
The tread depth should not fall below
0.12 in/3 mm although, for example,
European regulations only require 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.
As winter tires display a noticeable
loss in their ability to cope with cold-
weather driving conditions once the
tread wears to below 0.16 in/4 mm, you
should always have such tires replaced
to ensure continued safety.
Wear indicators at the tread-groove
base are distributed over the tire's cir-
cumference and are marked on the side
of the tire with TWI – Tread Wear Indi-
cator. If the tire tread has worn down
to the wear indicators, then the legally
permissible tread depth limit of
0.063 in/1.6 mm has been reached.
Online Edition for Part No. 01 41 0 159 867 - © 07/05 BMW AG
147n