I'm not sure if this is your question, but, more than forces, I think it's stability that prevents a rolling wheel from falling over. To elaborate on this, I will say that I cannot argue the role friction plays in making sure the wheel doesn't just slip and fall, but I would say that a lot of it has to do with the center of gravity. Remember that, for an object to be stabe and not fall, the center of gravity must be perpendicularly above the bottom of the object. By this, I mean the following. Say you have an object that is on the floor. Now, at one moment in time, you mark the center of gravity of the oject. Now, you drop a perpendicular from the center of gravity to the floor. Is this in a region where part of the object lies or is out "out of range" of the object? If the former, it will not tip. If the latter, boom! Torques also play a role in this. If you have a torque, that's what'll move the center of gravity. But, at a given moment of time, it'll only fall if the center of gravity is not above the bottom of the object.
Hope this helped!