A dishwasher appliance and a method for mounting a slide rail within a dishwasher appliance are provided. A rack assembly of the dishwasher appliance includes a bracket with a post. A slide rail is mounted to the bracket, and the slide rail and the bracket are positioned within a wash chamber of the dishwasher appliance. The post extends through the tub, and a sleeve is positioned opposite the bracket on the tub and engages the post. The sleeve hinders retraction of the post through the tub.