2009 Mercedes SLR McLaren Owner's Manual - Page 261

Operation Tires and wheels Life of tire The service life of a tire is dependent upon varying factors including but not limited to: Driving style Tire inflation pressure Distance driven Warning! approximately 1/16 in (1.6 mm), at which point the tire is considered worn and should be replaced. Recommended minimum tire tread depth: Summer tires 1/8 in (3 mm) Winter tires 1/6 in (4 mm) G Warning! G 1 TWI (Tread Wear Indicator) The treadwear indicator appears as a solid band across the tread. Tires should be replaced after 6 years, regardless of the remaining tread. Tread depth Do not allow your tires to wear down too far. Adhesion properties on wet roads are sharply reduced at tread depths of less than 1/8 in (3 mm). Treadwear indicators (TWI) are required by law. These indicators are located in six places on the tread circumference and become visible at a tread depth of Although the applicable federal motor safety laws consider a tire to be worn when the treadwear 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. 261