2009 BMW 5 Series Owner's Manual - Page 230

Wheels and tires DOT code: e.g. DOT xxxx xxx 1008 Traction The traction grades, from highest to lowest, are AA, A, B, and C. These grades represent the tire's ability to stop on wet pavement, as measured under controlled conditions on specified government test surfaces of asphalt and concrete. A tire marked C may have poor traction performance. The traction grade assigned to this tire is based on straight-ahead braking traction tests, and does not include acceleration, cornering, hydroplaning, or peak traction characteristics.< Manufacturer code for tire make Tire size and tire design Tire age Tire age The manufacturing date of tires is contained in the tire coding: DOT ...1008 indicates that the tire was manufactured in week 10 of 2008. BMW recommends that you replace all tires after 6 years at most, even if some tires may last for 10 years. Temperature The temperature grades are A, the highest, B, and C, representing the tire's resistance to the generation of heat and its ability to dissipate heat when tested under controlled conditions on a specified indoor laboratory test wheel. Sustained high temperature can cause the material of the tire to degenerate and reduce tire life, and excessive temperature can lead to sudden tire failure. The grade C corresponds to a level of performance which all passenger car tires must meet under the Federal Motor Vehicle Safety Standard No. 109. Grades B and A represent higher levels of performance on the laboratory test wheel than the minimum required by law. The temperature grade for this tire is established for a tire that is properly inflated and not overloaded. Excessive speed, underinflation, or excessive loading, either separately or in combination, can cause heat buildup and possible tire failure.< Uniform Tire Quality Grading Quality grades can be found where applicable on the tire sidewall between tread shoulder and maximum section width. For example: Tread wear 200 Traction AA Temperature A DOT Quality Grades Tread wear Traction AA A B C Temperature A B C All passenger car tires must conform to Federal Safety Requirements in addition to these grades.< Tread wear The tread wear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test course. For example, a tire graded 150 would wear one and one-half (1γ) times as well on the government course as a tire graded 100. The relative performance of tires depends upon the actual conditions of their use, however, and may depart significantly from the norm due to variations in driving habits, service practices and differences in road characteristics and climate. RSC - run-flat tires You will recognize run-flat tires by a circular symbol containing the letters RSC on the side of the tire, refer to page 229. M+S Winter and all-season tires. These have better winter properties than summer tires. 228 Online Edition for Part no. 01 41 2 600 721 - © 08/08 BMW AG