Due to increasingly demanding requirements for driving safety, precise and robust control of tire traction forces is essential to implement high-performance vehicle-control systems. However, traditional slip-ratio-based methods cannot guarantee achievement of desired traction forces due to a lack of tire force feedback. This paper proposes an observer-based traction force control scheme that is robust with respect to variations of road conditions and tire model uncertainties. Moreover, achievement of desired traction forces is guaranteed. Simulation results verify the robust and satisfactory performance, even under suddenly changing road conditions, as well as parametric and nonparametric tire model uncertainties.