Toe-OUT on a gear will almost GUARANTEE ground looping! Look at the facts... Refer to the picture below. The top 3 segments show a plane with TOE-IN. The bottom 3 show TOE-OUT.

In frames A and D the angles of the wheels are even in relation to the direction of travel and therefore have equal drag.

Now, let's compare frames B and E. In frame B the nose of the plane has shifted slightly to the right. This causes the Left wheel to toe-in even more, while the Right wheel "Straightens out" with the direction of movement. this creates more drag on the Left wheel and less on the Right, causing the plane to want to return to a straight track. Whereas, in frame E, with the wheels Toe-out, as the nose drifts to the right, more drag is placed on the Right wheel, while less is placed on the Left wheel causing the plane to want to go further to the right, and creating a ground loop.

Keep your taildragger wheels SLIGHTLY toe-in. NEVER toe out.

Remember, those full scale planes have a LOT more momentum than our little models have.