Combine pineapple juice, water, tequila, orange liqueur, frozen margarita mix, and limeade in a very large plastic container. Cover and freeze at least 24 hours or until frozen to a slushy consistency.
Moisten rims of margarita glasses with lime juice, and dip into coarse salt. Pour margarita mixture into glasses and garnish with lime wedges if desired.
A large clean ice cream pail works great for this recipe.