Unbalanced forces act on an object when the net force acting on the object is not zero.
In the given options, the situation where unbalanced forces are acting on the tire is:
Two people stand on the same side of a large tire. One person pushes the tire, and the other pulls the tire with equal force.
In this case, one force is acting in one direction (push) while the other force acts in the opposite direction (pull), resulting in an unbalanced force that would cause the tire to move in the direction of the stronger force.