Abstract
<jats:p>The paper aims to explain in the simplest possible way how tyres influence, to the greatest extent, the dynamic behaviour of cars, i.e. vehicle handling, during power-on or power-off. Starting from the ISO 4138 steering pad test, controlled power-on and power-off manoeuvres are introduced to reproduce typical manoeuvres relevant for active safety. Handling diagrams are used to make clear how tyres determine the oversteer and understeer character of a car. A simple two degrees-of-freedom analytical vehicle model and a complex high-fidelity fourteen degrees-of-freedom model have been used. Driver-in-the-Loop simulations were performed at a dynamic driving simulator. The study considers three representative driveline configurations, namely front-wheel drive (FWD), rear-wheel drive (RWD), and all-wheel drive (AWD). A key outcome of the study is that the fundamental mechanisms governing understeer and oversteer behaviour can be effectively captured using a simple two degrees-of-freedom model combined with appropriate tyre characteristics. The results show that the handling diagrams are a proper tool to describe handling manoeuvres during power-on or power-off. Variations in understeer and oversteer behaviour induced by power modulation can be interpreted as a direct consequence of tyre characteristics. The findings of this work highlight the pivotal role of the tyre in vehicle dynamics and active safety.</jats:p>