Tire brake force characteristic data are presented that should be helpful in the design of wheel slip control systems. Correlation of these data has been established with antilock system performance. Experimentally measured μ-slip curves are given for a large number of tire/road pairings. These measurements cover a wide range of commercial tire types on dry and wet road surfaces and glare ice. It is shown how wet road characteristics are affected by road construction, water cover depth, and tread wear. The measuring system used to obtain these data is described and variability of the experimental measurements is discussed.