Debug Vehicle tire mesh colors?

What do the colors (red, blue, green) mean in the ShowDebug Vehicle screen for the outline of the tires?

I have a stabilizer (static mesh) I am trying to get to function that I can not get figured out. When I turn physics on for the stabilizers (static mesh) to support the vehicle, the back tires in the debug vehicle screen turn red (just spin-no movement) which is expected. When I turn physics - collisions off (according to printstring no collisions or physics) and the stabilizers are lifted, the vehicle still won’t move.