Combine the vinegar, olive oil, salt, and sugar in a small mixing bowl. Add the apple, toss to coat, then drain, discarding the excess dressing.
Dip one sheet of rice paper briefly in a bowl of room temperature water to wet it, then lay it flat on a plate. Arrange ¼ cup of the lettuce in a narrow rectangle in the center of the rice paper, then top it with one-eighth of the chicken, apple, and grapes. Fold the bottom edge of the rice paper up over the filling, tucking it under the far side of the lettuce. Fold in both sides to seal the ends, then roll up. Repeat with remaining rice papers and fillings.