Working in 2 batches, place 1 quart ice cubes in a blender. Add 1/2 can limeade, 6 ounces tequila, and 2 tablespoons Cointreau. Blend at the highest speed until the drink is almost smooth.

Pour the blended mixture into a pitcher and repeat with the remaining ingredients. Store in the freezer.

Salt the margarita glasses by pouring a single layer of salt on a small plate. Moisten each glass rim with lime and dip each rim in the salt.