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:
BAS (Brake Assist System)
   Observe the "Important safety notes" 
section
BAS operates in emergency braking 
situations. If you depress the brake pedal 
quickly, BAS automatically boosts the braking 
force, thus s ...
   
Important safety notes
   ! A license agreement must exist in order 
to activate the mbrace service. Ensure that 
your system is activated and ready for use, 
and press the  MB Info call button 
to 
register. If any of th ...
   
Overview of Tire Quality Grading Standards
   
The Uniform Tire Quality Grading is a U.S. Government requirement. Their purpose 
is to provide drivers with consistent and reliable information regarding tire performance. 
Tire manufacturers are ...
   
