Experimental investigations on tire/road friction dependence from thermal conditions carried out with real tread compounds in sliding contact with asphalt specimens

The understanding of tire’s adherence with a rough surface is a common goal for several fields in the automotive sector. In fact, grip is synonym of safety and performance, playing a decisive role for braking distance and vehicle stability, fuel consumption, wear rate [1], noise generation and for the vehicle dynamics control system (e.g. ABS, TCS, AYC and other) [2]. This paper deals with tire tread grip experimental investigation and evaluation under different conditions that influence it during the sliding contact [3]. In this regard the test campaign involves the use of different tire compounds (in terms of viscoelastic characteristics), tested in several conditions: different contact pressure, sliding speed, temperature, sliding contact length and road surface. The test bench employed by the UniNa Vehicle Dynamic Research Group is an upgrade of the British Pendulum, an instrument for outdoor tribological tests on road sections. The principal sensors installed on the test bench are an encoder, for the evaluation of the sliding speed of the tire specimen, and a load cell, for the measurement of the force arising at tire/road interface in the longitudinal and vertical directions [4]. In fact, the grip shall be determined as the ratio of the longitudinal force and corresponding load on the tire. The paper's aim is the description of the experimental campaign after an accurate introduction on the test setup and an illustration of the equipment. Finally, the preliminary results and the methodologies used to process the acquired data are described.