A bracing salted rim may be a tradition, but it can overwhelm the nuances of a good tequila. On the other hand, a touch of superfine sugar can be a nice complement to citrus-centered margaritas.
Remove zest from 1 grapefruit. Place zest in a glass; add tequila. Cover, and let stand 1 hour. Strain. Rub zest over half of each glass rim; dip rims in sugar.
Cut peel and pith from grapefruits; cut flesh into segments. PurÃ©e grapefruits, tequila, sugar, triple sec, and ice in a blender until smooth. Pour into glasses.