2009 BMW Z4 Owner's Manual - Page 195

Tire identification marks Knowledge of the labeling on the side of the tire makes it easier to identify and choose the right tires. 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 Tire size e.g. 225/45 R 17 91 V Nominal width in mm Aspect ratio in Ξ Radial belt construction Rim diameter in inches Load rating, not on ZR tires Speed code letter, in front of the R on ZR tires 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. Speed code letter Q = up to 100 mph or 160 km/h T = up to 118 mph or 190 km/h H = up to 131 mph or 210 km/h V = up to 150 mph or 240 km/h W = up to 167 mph or 270 km/h Y = up to 186 mph or 300 km/h Tire Identification Number Tires with DOT codes meet the guidelines of the US Department of Transportation. DOT code: e.g. DOT xxxx xxx 0709 Traction The traction grades, from highest to lowest, are AA, A, B, and C. Those 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's 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 ... 0709 means that the tire was manufactured in week 7 of 2009. BMW recommends that you replace all tires after 6 years at most, even if some tires may last for 10 years. 193 Online Edition for Part no. 01 41 2 602 116 - © 01/09 BMW AG Reference Mobility Communications Entertainment Navigation Driving tips Controls DOT Quality Grades At a glance