System and method for operating vehicle drive wheels

An agricultural machine comprising:

• a chassis supported by a pair of front wheels and a pair of steerable rear wheels;
• a first hydraulic motor for driving at least one of the front wheels to move the chassis at a designated forward speed;
• a second hydraulic motor configured to operate independently of the first hydraulic motor and to drive a first of the pair of rear wheels;
• a third hydraulic motor configured to operate independently of the first and second hydraulic motors and to drive a second of the pair of rear wheels;
• a user interface;
• and
• a controller for controlling operation of the second and third hydraulic motors to provide rear wheel supplemental propulsion, the controller configured to receive a rear wheel supplemental propulsion command from the user interface and, in response to receiving the rear wheel supplemental propulsion command, actuate the second and third hydraulic motors to drive the first and second rear wheels to apply forward pressure on the chassis regardless of the forward speed, the controller further configured to actuate the second and third hydraulic motors to maintain the first and second rear wheels turning at a rate corresponding to a higher travel speed than the at least one front wheel and the actual travel speed of the vehicle to thereby apply the forward pressure on the chassis while causing both the first and second rear wheels to continuously slip while operating with rear wheel supplemental propulsion.