A hydraulic system for controlling a pair of steerable caster wheels of an agricultural machine includes a fluidic tie rod fluid circuit interconnecting both a left side actuator and a right side actuator with a rear steering control valve in fluid communication, and forming a fluid tie rod between the left side actuator and the right side actuator. A tie rod control valve is disposed in the fluidic tie rod fluid circuit and is controllable between a first position allowing fluid communication through the fluidic tie rod fluid circuit to communicate fluid between the left side actuator, the right side actuator, and the rear steering control valve and a second position blocking fluid communication to the rear steering control valve while connecting the left side actuator and the right side actuator in fluid communication to increase stiffness of the fluid tie rod therebetween.