2011 Mercedes SL-Class Owner's Manual - Page 200

198 Tires and wheels Tire inspection Every time you check the tire inflation pressure, you should also inspect your tires for the following: Rexcessive Rcord treadwear (Y page 198) or fabric showing through the tire's rubber bulges, cuts, cracks or splits in the tread or side of the tire Rbumps, Operation Replace the tire if you find any of the above conditions. Make sure you also inspect the spare tire periodically for condition and inflation. Spare tires will age and become worn over time even if never used, and thus should be inspected and replaced when necessary. 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 approximately 1/ in (1.6 mm), at which point the tire is 16 considered worn and should be replaced. The recommended minimum tire tread depth for summer tires is 1/8 in (3 mm). The recommended minimum tire tread depth for winter tires is 1/6 in (4 mm). Life of tire G Warning! Tires and spare tire should be replaced after 6 years, regardless of the remaining tread. The service life of a tire is dependent upon varying factors including but not limited to: RDriving RTire style driven inflation pressure Treadwear indicator : appears as a solid band across the tread. RDistance Storing tires ! Keep unmounted tires in a cool, dry place with as little exposure to light as possible. Protect tires from contact with oil, grease and fuels. Cleaning tires ! Never use a round nozzle to power wash tires. The intense jet of water can result in damage to the tire. Always replace a damaged tire. Tread depth Although the applicable federal motor vehicle 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. G Warning!