Tire tread
WARNING
Although the applicable federal motor vehicle
safety laws consider a tire to be worn when
the tread wear indicators (TWI) become
visible at approximately 1/16 in (1.6 mm), we
recommend that you do not allow your tires
to wear down to that level. As tread depth
approaches 1/8 in (3 mm), the adhesion
properties on a wet road are sharply reduced.
Depending upon the weather and/or road
surface (conditions), the tire traction varies
widely.
Do not use tires that are excessively worn as the tire traction on wet road surfaces decreases significantly when the tread depth is less than 1/8 inch (3 mm).
Tread wear indicators (TWI) are required by law. Six indicators are positioned on the tire tread. They become visible as soon as a tread depth of approximately 1/16 inch (1.6 mm) has been reached. If this is the case, the tire is so worn that it must be replaced.
The recommended tread depth for summer tires is at least 1/8 inch (3 mm). The recommended tread depth for winter tires is at least 1/6 inch (4 mm).

Bar marking 1 for tread wear is integrated into the tire tread.
See also:
Attaching the cargo net
– Pull the cargo net up by tab 1 and hook it
into eyelets 2 using both hands. ...
Cleaning the wheels
Do not use acidic wheel cleaning products
to remove brake dust. This could damage
wheel bolts and brake components.
Do not park the vehicle for an extended
period straight after cleaning it, ...
M+S tires
At temperatures below 45 ‡(+7 †), use winter tires or all-season tires. Both
types of tire are identified by the M+S marking.
Only winter tires bearing the snowflake
symbol in addition to the M+ ...
