USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Portions of the Department of Transportation are currently in shutdown/furlough status due to a lapse in appropriations. Please continue to monitor this page for updates on DOT’s operating status.
U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Regulatory Guidance

Welcome to the FMCSA Guidance Portal. This web portal is a searchable, indexed database that contains and links to all guidance documents in effect from the Federal Motor Carrier Safety Administration. The guidance documents lack the force and effect of law, unless expressly authorized by statute or incorporated into a contract.

To comment on any guidance document, or to request issuance, reconsideration, modification, or rescission of any guidance document, please identify the guidance document in your request and send it to: FMCSAguidance@dot.gov. NOTE: The FMCSAguidance mailbox is not intended to serve as a mailbox for general inquiries. For inquiries that go beyond the limited purpose of the FMCSAguidance mailbox, please call FMCSA's Information Line (800-832-5660) or visit FMCSA's "Contact Us" page to send your inquiry to the appropriate mailbox.

Subject Agency Identifier Topic Issued Date
Is there a minimum number of fasteners required to fasten the upper fifth wheel plate to the frame of a trailer? FMCSA-VEH-393.70-Q01 Securing upper fifth wheel plate to trailer frame
When two safety chains are used, must the ultimate combined breaking strength of each chain be equal to the gross weight of the towed vehicle(s) or would the requirements be met if the combined breaking strength of the two chains is equal to the gross wei FMCSA-VEH-393.70-Q02 Required strength of safety chains
Section 393.70(d) requires that every full trailer must be coupled to the frame FMCSA-VEH-393.70-Q03 Two sets of safety chains attached to draw bar
May a fifth wheel be considered as a coupling device when towing a semi-trailer in a driveaway-towaway operation? FMCSA-VEH-393.71-Q01 Use of fifth wheel when towing a trailer in driveaway-towaway operation
If a CMV has a defective tire, may the driver remove the defective tire from the axle and drive with three tires on an axle instead of four? FMCSA-VEH-393.75-Q01 Removal of defective tire from set of dual tires
May a vehicle transport HM when equipped with retreaded tires? FMCSA-VEH-393.75-Q02 Retreaded tires to transport hazardous material
May tires be filled with materials other than air (e.g., silicone, polyurethane)? FMCSA-VEH-393.75-Q03 Filling tires with material other than air
Do tires marked ‘‘NHS’’ (not for highway service) mean that highway use is prohibited by § 393.75? FMCSA-VEH-393.75-Q04 Use of tires not for highway service on the highway
If a compartment in a CMV is no longer used as a sleeper berth, must it be maintained and equipped as a sleeper berth as required in § 393.76? FMCSA-VEH-393.76-Q01 Maintenance of sleeper berth not used as such
Do the FMCSRs specify what type of horn is to be used on a CMV? FMCSA-VEH-393.81-Q01 Type of horn on CMV