Influence of circumferential tread pattern stiffness on tyre road noise generation under driving torque

Concerning the sound emission of electric vehicles there aretwo main challenges: On the one hand, the exterior noise is on a very low noise level and approaching electric vehicles might not be recognized in city traffic. On the other hand, compared to internal combustion engines, electric drives develop a considerably high torque from the standstill which might increases tireroad noise of about 10 dB in the near-field. Since combustion engine noise gets eliminated, tireroad noise will not be masked anymore during acceleration but instead occurs as a disturbing, dominant acoustic source.The paper describes first an inner drum test rig which allows the reproducible measurement of tireroad noise on real road surfaces at driving and braking torque. Then, test results of special tires with different rubber compounds and pattern designs are presented. The influence of pattern stiffness and tiretorque on tireroad noise generation is analysed. Additional the inner drum test results were validated by pass-by measurements on different road surfaces. Finally, the effects and mechanisms of the noise phenomena are discussed and tirepattern design concepts for low noise emission under driving torque are derived.