In this study, the relationships between friction and viscoelastic properties such as loss tangent tan δ and storage modulusE′ were examined. Wet skid resistance was measured using the British Pendulum Tester. The rubber specimens were rubbed againstfive silicone carbide cloths of differing abrasive grain sizes. The viscoelastic properties of the rubber specimens were measured with a viscoelasticspectrometer. From the data on wet skid resistance and viscoelastic properties, it is found that the coefficient of friction μ varies as follows:
μ = a + b · tan δ/E′
where a and b are constants. Tan δ/E′ was related to the hysteresis term of friction, and the μ‐frequency curves were compared with the tan δ/E′ –frequency curves.