Int. J. Heavy Vehicle Systems, Vol. 24, No. 4, 2017 305 Copyright © 2017 Inderscience Enterprises Ltd. Suspension and tyres: stability of heavy vehicles Gonzalo Moreno* Federal University of Santa Catarina, Florianopolis, SC, 88040-900, Brazil and University of Pamplona, Pamplona, 543050, Colombia Email: gmoren@hotmail.com *Corresponding author Lauro Cesar Nicolazzi, Rodrigo de Souza Vieira and Daniel Martins Federal University of Santa Catarina, Florianopolis, SC, 88040-900, Brazil Email: lauro@grante.ufsc.br Email: rvieira@grante.ufsc.br Email: daniel.martins@ufsc.br Abstract: The static stability factor (SSF) of a vehicle is mainly dependent on the lateral and vertical location of the vehicle’s centre of gravity (CG) and this point is, in turn, influenced by many factors associated with, for instance, the vehicle suspension, tyres and the fifth-wheel among others. These systems allow the movement of the vehicle body along with its CG, which modifies substantially the SSF calculation. This paper describes the modelling of a leaf spring suspension system and the tyres using mechanism theory and subsequent kinematic analysis using the Davies method. The proposed model is planar and allows relative motion between the sprung and unsprung masses of the vehicle. This paper also compares the classic vehicle stability analysis with the proposed model, and the influence of the suspension and tyres in relation to the vehicle stability is evaluated. Keywords: leaf spring; suspension; tyres; kinematics; SSF; static stability factor; Davies method; heavy vehicle; graph theory. Reference to this paper should be made as follows: Moreno, G., Nicolazzi, L.C., Vieira, R.S. and Martins, D. (2017) ‘Suspension and tyres: stability of heavy vehicles’, Int. J. Heavy Vehicle Systems, Vol. 24, No. 4, pp.305–326. Biographical notes: Gonzalo Moreno received his Mechanical Engineering degree from the Francisco de Paula Santander University, Colombia (1999), Master’s in Mechanical Engineering from the University of the Andes, Colombia (2004) and currently PhD student at the Mechanical Engineering from the Federal University of Santa Catarina (2015). He is a Lecturer of the Department of Mechanical Engineering at the University of Pamplona,