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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
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
Are there established criteria in the FMCSRs to determine the minimum sound level of horns on CMVs? FMCSA-VEH-393.81-Q02 Do FMCSRs specify minimum sound levels for horns?
Is a heat shield mandatory on a vertical exhaust stack? FMCSA-VEH-393.83-Q01 Heat shield on vertical exhaust stack?
Does § 393.83 specify the type of exhaust system, vertical or horizontal, to be used on trucks or truck tractors? FMCSA-VEH-393.83-Q02 Vertical vs. horizontal exhaust systems
May a triangular-shaped flag or device be used by itself to mark an oversized load? FMCSA-VEH-393.87-Q01 Triangular flag to mark oversized load
Does § 393.88 restrict the use of closed circuit monitor devices being used as a safety viewing system that would eliminate blind-side motor carrier accidents? FMCSA-VEH-393.88-Q01 Use of closed-circuit TV to monitor blind spots