Always handwash tights or place them in a mesh bag before machine washing on gentle cycle. Allow the tights to hang dry.
If a small snag or run appears in the tights, apply a small amount of clear nail polish around the edges to prevent further tearing. This should allow you to slightly extend the life of the tights.
Note: Always carry an extra pair of tights to a recital or performance. Tights tend to snag easily, especially when worn on the legs of active little dancers.