Haulmark sells parts for its trailers from its online store. The company provides a phone number for customers to call to inquire about parts not listed on the website. Parts available online include large items such as doors and sheet metal walls, as well as small items such as hinges.
Categories of parts available include lighting, tires, windows, vents and trim. Some parts fit all or most Haulmark trailers, while others fit specific trailer sizes. For example, roof caps come in sizes ranging from 60 to 100 inches. As of 2015, the product pages for individual parts do not identify which Haulmark trailers the parts do or do not fit.