Varying terrain conditions influencing the ground friction challenge model-based control methods for precise autonomous driving of agricultural vehicles on off-road terrains. We apply moving horizon estimation (MHE) to cope with these uncertainties in a predictive control framework for autonomous driving of a sensor-equipped tractor using a (nonlinear) rigidbody dynamic model featuring a simple tire slip model. Using the ACADO Code Generation tool feedback times in the range of few miliseconds are achieved. Estimation results on real-world experimental data are presented.