Deur, J., Ivanović, V., Troulis, M., Miano, C., Hrovat, D., Asgari, J., "Extensions of LuGre Tire Friction Model Related to Variable Slip Speed Along Contact Patch Length", 3rd International Tyre Colloquium 'Tyre Models for Vehicle Dynamics Analysis' , (TMVDA), IAVSD, Vienna, 2004. Abstract. The recently developed LuGre model describes the 3D tire friction dynamics given in brush representation. The model has three-state lumped-parameter form and an analytical solution for tire static curves. It is simplified based on the assumption of constant slip speed along the contact patch length. This assumption is released in this paper in order to extend the model with several secondary, but potentially important effects such as camber, carcass compliance, conicity, ply-steer, and rolling resistance. Two approaches of introduction of variable slip speed effect are considered. The first one is based on stepwise approximation of slip speed along the contact patch length, and the second one includes a specific spatially-distributed additive deflection term. Both approaches provide preserving the three-state lumped-parameter model form and an analytical steady-state solution. Qualitative and quantitative validation results point to consistency and benefits of the proposed model extensions.