Unbalanced forces act on an object when the net force is not equal to zero. In the scenarios you provided, the situation that leads to unbalanced forces 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, the forces are acting in opposite directions (one pushing, one pulling), leading to a net force. This would result in the tire moving in the direction of the net force, indicating that the forces are unbalanced.