An agricultural harvester rear axle arrangement for an agricultural harvester having a body, the arrangement comprising: left and right rear wheels (18, 20); means (26, 28, 30, 90) for supporting the wheels (18, 20) for rotation about a generally vertical steering axis (38, 40, 78, 94); actuator means (38, 40, 70, 72, 94, 34, 36, 70, 72) for steering the wheels (18, 20); an electronic controller coupled to the actuator means (38, 40, 70, 72, 94, 34, 36, 70, 72) to steer the wheels (18, 20); an operator input device coupled to the electronic controller to indicate a desired steering angle of the wheels (18, 20); characterized in that the means (26, 28, 30, 90) for supporting the wheels (18, 20) for rotation about a generally vertical steering axis (38, 40, 78, 94) are also for supporting the wheels (18, 20) for extension and retraction from the body of the harvester, that the actuator means (38, 40, 70, 72, 94, 34, 36, 70, 72) for steering the wheels (18, 20) are also for extending and retracting the wheels (18, 20), that the electronic controller coupled to the actuator means (38, 40, 70, 72, 94, 34, 36, 70, 72) is also adapted to extend and retract the wheels (18, 20), that an operator input device is coupled to the electronic controller to indicate to the electronic controller a first mode of operation requiring substantially simultaneous steering, extension and retraction, and at least a second mode of operation in which steering is not substantially simultaneous with extension and retraction, and that the electronic controller is arranged to base a desired degree of extension for the desired steering angle at least upon the signal of the operator input device indicating the desired steering angle; and to substantially simultaneously steer the rear wheels (18, 20) to the desired angle and extend the wheels (18, 20) to the desired degree of extension. left and right rear wheels (18, 20); means (26, 28, 30, 90) for supporting the wheels (18, 20) for rotation about a generally vertical steering axis (38, 40, 78, 94); actuator means (38, 40, 70, 72, 94, 34, 36, 70, 72) for steering the wheels (18, 20); an electronic controller coupled to the actuator means (38, 40, 70, 72, 94, 34, 36, 70, 72) to steer the wheels (18, 20); an operator input device coupled to the electronic controller to indicate a desired steering angle of the wheels (18, 20); characterized in that the means (26, 28, 30, 90) for supporting the wheels (18, 20) for rotation about a generally vertical steering axis (38, 40, 78, 94) are also for supporting the wheels (18, 20) for extension and retraction from the body of the harvester, that the actuator means (38, 40, 70, 72, 94, 34, 36, 70, 72) for steering the wheels (18, 20) are also for extending and retracting the wheels (18, 20), that the electronic controller coupled to the actuator means (38, 40, 70, 72, 94, 34, 36, 70, 72) is also adapted to extend and retract the wheels (18, 20), that an operator input device is coupled to the electronic controller to indicate to the electronic controller a first mode of operation requiring substantially simultaneous steering, extension and retraction, and at least a second mode of operation in which steering is not substantially simultaneous with extension and retraction, and that the electronic controller is arranged to base a desired degree of extension for the desired steering angle at least upon the signal of the operator input device indicating the desired steering angle; and to substantially simultaneously steer the rear wheels (18, 20) to the desired angle and extend the wheels (18, 20) to the desired degree of extension.