If you watch the Today Show’s investigative report on truck SIDE UNDERIDE, you will discover that the federal government does not require side guards on large trucks. And trailer manufacturers do not install them on the trailers they produce.
February 13, 2017 Update: I just received a notification of a new posting to the Federal Register of a Public Comment from someone asking DOT/NHTSA to mandate side guards! I am assuming that someone responded to my request for people to do so to help bring about change. 🙂
See it here: https://www.regulations.gov/document?D=NHTSA-2015-0118-0049 Actually, a second person also submitted a comment.
You can do it, too! SUBMIT a Public Comment to DOT/NHTSA here: https://www.regulations.gov/docket?D=NHTSA-2015-0118 After you get to this site, click on the COMMENT NOW button.