A monitoring system for monitoring steering conditions of a vehicle, the system comprising: a location-determining receiver for estimating a position and velocity of the vehicle and a yaw or heading of the vehicle for a corresponding sampling interval; an inertial measurement unit (53, 153) for estimating a yaw rate for the vehicle for the sampling interval; and an accelerometer for measuring roll angle of the vehicle for the sampling interval; characterized by comprising: a stability index estimator for determining a stability index based on the estimated position, the estimating heading, and the estimated yaw rate for the sampling interval; a surface roughness estimator for estimating a variance or standard deviation of the roll of roll angle change based on the measured roll angle for the sampling interval; a rotational speed sensor for measuring a drivetrain-derived wheel speed for the sampling interval; a wheel slip estimator for estimating a wheel slip indicator based on a numerator of drivetrain-derived wheel speed minus estimated velocity, which numerator is collectively divided by the drivetrain-derived wheel speed of the denominator; and a performance evaluation module for determining a performance rating based on the determined stability index, the estimated surface roughness index and the estimated wheel slip for the sampling interval. a location-determining receiver for estimating a position and velocity of the vehicle and a yaw or heading of the vehicle for a corresponding sampling interval; an inertial measurement unit (53, 153) for estimating a yaw rate for the vehicle for the sampling interval; and an accelerometer for measuring roll angle of the vehicle for the sampling interval; characterized by comprising: a stability index estimator for determining a stability index based on the estimated position, the estimating heading, and the estimated yaw rate for the sampling interval; a surface roughness estimator for estimating a variance or standard deviation of the roll of roll angle change based on the measured roll angle for the sampling interval; a rotational speed sensor for measuring a drivetrain-derived wheel speed for the sampling interval; a wheel slip estimator for estimating a wheel slip indicator based on a numerator of drivetrain-derived wheel speed minus estimated velocity, which numerator is collectively divided by the drivetrain-derived wheel speed of the denominator; and a performance evaluation module for determining a performance rating based on the determined stability index, the estimated surface roughness index and the estimated wheel slip for the sampling interval. a stability index estimator for determining a stability index based on the estimated position, the estimating heading, and the estimated yaw rate for the sampling interval; a surface roughness estimator for estimating a variance or standard deviation of the roll of roll angle change based on the measured roll angle for the sampling interval; a rotational speed sensor for measuring a drivetrain-derived wheel speed for the sampling interval; a wheel slip estimator for estimating a wheel slip indicator based on a numerator of drivetrain-derived wheel speed minus estimated velocity, which numerator is collectively divided by the drivetrain-derived wheel speed of the denominator; and a performance evaluation module for determining a performance rating based on the determined stability index, the estimated surface roughness index and the estimated wheel slip for the sampling interval.