NHTSA Interpretation File Search
Overview
NHTSA's Chief Counsel interprets the statutes that the agency administers and the standards and regulations that it issues. Members of the public may submit requests for interpretation, and the Chief Counsel will respond with a letter of interpretation. These interpretation letters look at the particular facts presented in the question and explain the agency’s opinion on how the law applies given those facts. These letters of interpretation are guidance documents. They do not have the force and effect of law and are not meant to bind the public in any way. They are intended only to provide information to the public regarding existing requirements under the law or agency policies.
Understanding NHTSA’s Online Interpretation Files
NHTSA makes its letters of interpretation available to the public on this webpage.
An interpretation letter represents the opinion of the Chief Counsel based on the facts of individual cases at the time the letter was written. While these letters may be helpful in determining how the agency might answer a question that another person has if that question is similar to a previously considered question, do not assume that a prior interpretation will necessarily apply to your situation.
- Your facts may be sufficiently different from those presented in prior interpretations, such that the agency's answer to you might be different from the answer in the prior interpretation letter;
- Your situation may be completely new to the agency and not addressed in an existing interpretation letter;
- The agency's safety standards or regulations may have changed since the prior interpretation letter was written so that the agency's prior interpretation no longer applies; or
- Some combination of the above, or other, factors.
Searching NHTSA’s Online Interpretation Files
Before beginning a search, it’s important to understand how this online search works. Below we provide some examples of searches you can run. In some cases, the search results may include words similar to what you searched because it utilizes a fuzzy search algorithm.
Single word search
Example: car
Result: Any document containing that word.
Multiple word search
Example: car seat requirements
Result: Any document containing any of these words.
Connector word search
Example: car AND seat AND requirements
Result: Any document containing all of these words.
Note: Search operators such as AND or OR must be in all capital letters.
Phrase in double quotes
Example: "headlamp function"
Result: Any document with that phrase.
Conjunctive search
Example: functionally AND minima
Result: Any document with both of those words.
Wildcard
Example: headl*
Result: Any document with a word beginning with those letters (e.g., headlamp, headlight, headlamps).
Example: no*compl*
Result: Any document beginning with the letters “no” followed by the letters “compl” (e.g., noncompliance, non-complying).
Not
Example: headlamp NOT crash
Result: Any document containing the word “headlamp” and not the word “crash.”
Complex searches
You can combine search operators to write more targeted searches.
Note: The database does not currently support phrase searches with wildcards (e.g., “make* inoperative”).
Example: Headl* AND (supplement* OR auxiliary OR impair*)
Result: Any document containing words that are variants of “headlamp” (headlamp, headlights, etc.) and also containing a variant of “supplement” (supplement, supplemental, etc.) or “impair” (impair, impairment, etc.) or the word “auxiliary.”
Search Tool
NHTSA's Interpretation Files Search
| Interpretations | Date |
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ID: aiam5197OpenMr. Charlie McBay Chief Engineer Barrett Trailers, Inc. P.O. Box 890670 Oklahoma City, OK 73189-0670; Mr. Charlie McBay Chief Engineer Barrett Trailers Inc. P.O. Box 890670 Oklahoma City OK 73189-0670; "Dear Mr. McBay: We have received your letter of June 13, 1993, askin that this Office review the two drawings you enclosed 'for compliance with the upcoming conspicuity requirement', and 'ask that our installation have your approval.' Under the National Traffic and Motor Vehicle Safety Act the manufacturer has the responsibility of determining whether its product conforms and then certifies its compliance with all applicable Federal motor vehicle safety standards. The Act does not provide authority for the agency to 'approve' or 'disapprove' any specific solution to methods of conformance. For this reason, we are unable to advise you in the manner you seek. However, the agency does provide interpretations when specific questions are asked with respect to the requirements of the standard, and we are pleased to respond accordingly to your inquiries. You have raised four issues for our comment. 1. You have called to our attention that the 'outside post' design of the trailers is configured so that the spacing of the posts along the length of the trailers is not the same. The retroreflective material will be evenly spaced in most areas, but breaks between material vary. You have asked whether this will 'suffice for evenly distributed.' Under S5.7.1.4.2(a) of Federal Motor Vehicle Safety Standard No. 108, retroreflective sheeting applied to each side of a trailer need not be continuous 'as long as not less than half of the length of the trailer is covered and the spaces are distributed as evenly as practicable.' As we have advised many times, under Standard No. 108 the determination of practicability is to be made by the manufacturer in fulfillment of its obligation to certify that its product conforms to all applicable Federal motor vehicle safety standards. NHTSA believes that, as a general rule, a manufacturer is in the best position to determine what is practicable for its particular design. However, if that determination appears erroneous on its face, NHTSA will question it. Were you to manufacture trailers with the side conspicuity treatment spacings depicted on your drawings, NHTSA would not question your determination of practicability. 2. You have asked 'if an area exists where a minimum 12' strip will not fit, can we install smaller material or must this area stay blank?' As noted above, under S5.7.1.4.2, a strip of retroreflective material need not be continuous 'as long as not less than half of the length of the trailer is covered.' Therefore, if exclusion of the area in question would not result in less than half of the length of the trailer being covered, the area may be left blank. If additional sheeting is required for a trailer to meet the length requirement, or if a manufacturer simply wishes to add it, it need not be 'a minimum 12' strip.' S5.7.1.3(d) of Standard No. 108 specifies that each segment of retroreflective sheeting shall have a length of 300 mm (i.e., 12 inches) +/- 150 mm. Therefore, a segment of sheeting as short in length as 150 mm (6 inches) could be applied to the area in question in compliance with the standard. An even shorter segment is permitted if necessary 'to clear obstructions' if that should be the reason in your instance where a strip of 300 mm will not fit. If the length of the area in question is smaller than 150 mm and its coverage is required for the conspicuity treatment on the trailer to meet the length requirement, then any length of material is acceptable. 3. You have asked us to note that the white strips in the upper rear corners do not meet. You have asked 'Must white be touching or can there be a gap between the strips?' Figure 30 'Typical Trailer Conspicuity Treatments' depicts two configurations in which the white strips of retroreflective material intersect at right angles in the upper rear corners. The requirement that Figure 30 illustrates is set forth in S5.7.1.4.1(b), which specifies, in pertinent part, 'two pairs of white strips of sheeting, each pair . . . applied horizontally and vertically to the right and left upper contours of the body . . . as close to the top of the trailer and as far apart as practicable.' There is no explicit requirement in this paragraph that the horizontal and vertical strips intersect or touch. There is an implicit requirement in the specification that the strips be 'as close to the top and as far apart as practicable', but the requirement is subject to the manufacturer's determination of practicability. In other words, if the manufacturer's determination of practicability results in a gap between the strips, NHTSA will not question this determination unless it appears clearly erroneous. 4. You represent that your design makes it impossible 'to make a nice continuous square corner', and that ' i nstallation of the white corners is also closer than 3' from red top rail lights.' You ask whether there is 'any tolerance on the 3' dimensions? There is no tolerance on this requirement. S5.7.1.4(b) states that 'The edge of white sheeting shall not be located closer than 75 mm to the edge of the luminous lens area of any lamp that is required by this standard.' The diagrams you enclose depict the horizontal white strip directly below the clearance lamps, which are required by Standard No. 108, so that each design does not accord with Standard No. 108. We have some comments on each design. On 'Model 80MP6-DD' it appears to us that, under a determination of practicability, the white strips could be lowered until the required minimum spacing between it and the clearance lamp was achieved. There is no prohibition against placing the material on the roll-up door. The trailer identified as 'GNXS-207' raises a more difficult problem because there appears to be no place where the strips could be relocated. Consideration must be given, therefore, to relocation of the clearance lamps. Under Table II of Standard No. 108, clearance lamps are intended to 'indicate the overall width of the trailer'. Although clearance lamps should be 'as near the top . . . as practicable', they need not be ' w hen the rear identification lamps are mounted at the extreme height of a vehicle' (S5.3.1.4). The rear identification lamps on GNXS-207 are mounted at the extreme height of the vehicle. The clearance lamps could be relocated to the fender where the stop, turn, and taillamps are presently installed. In that location, the clearance lamps would also be better able to fulfill the intent that they indicate the overall width of the trailer, which appears to occur at the fender rather than at the upper part of the body. We hope that these interpretations are helpful. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam0395OpenMr. Keith D. Kroll, Director, Airstream Technical Center, 15939 Piuma Avenue, Cerritos, CA, 90701; Mr. Keith D. Kroll Director Airstream Technical Center 15939 Piuma Avenue Cerritos CA 90701; Dear Mr. Kroll: This is in response to your letter of June 25, 1971, to Mr. Douglas W Toms, Acting Administrator, National Highway Traffic Safety Administration, concerning lamp locations proposed for your 1972 Airstream trailer.; Federal Motor Vehicle Safety Standard No. 108, as amended October 31 1970 and February 3, 1971, effective January 1, 1972, requires that clearance lamps be mounted to indicate the overall width and as near the top as practicable. Paragraph S4.3.1.5 permits optional mounting height of rear clearance lamps when the rear identification lamps are mounted at the extreme height of a vehicle.; The front and rear clearance lamps mounted as shown on your drawin 10033, revision C, do not appear to meet these location requirements. These lamps could be mounted higher than shown and still indicate the overall width of the trailer at locations other than the upper right and left corners, perhaps as high as the front and rear windows.; In addition, the side reflex reflectors are to be located as far to th front and rear of the vehicle as practicable. Neither the front nor rear side reflex reflectors shown on the subject drawing appear to meet this requirement.; Sincerely, E. T. Driver, Director, Motor Vehicle Programs, Office o Operating Systems; |
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ID: aiam3413OpenMr. R. O. Sornson, Director, Regulatory Research and Analysis, Chrysler Corporation, P.O. Box 1919, Detroit, MI 48288; Mr. R. O. Sornson Director Regulatory Research and Analysis Chrysler Corporation P.O. Box 1919 Detroit MI 48288; Dear Mr. Sornson: This responds to your recent letter requesting an interpretatio concerning the seat belt warning system requirements of Safety Standard No. 208. You ask whether the standard permits the audible warning system to activate even when the seat belt is buckled. If the agency's response is negative, you ask that your letter be treated as a petition for rulemaking.; The answer to your question is no. The audible warning system canno activate if the seat belt is buckled. This same question was asked in a request for interpretation and petition for rulemaking submitted by American Motors Corporation in 1979. Enclosed is a copy of the agency's December 31, 1979, response to American Motors, which explains the rationale for this interpretation.; The agency's position has not changed since the response to America Motors, although as part of our regulatory review, we do plan to look closely at the warning system requirements of Standard No. 208 in their entirety. That review could lead to major changes in the warning system requirements, and we will give serious consideration to your request during our analysis. At the current time, however, we deny your petition for rulemaking since the requested change is inconsistent with the rationale for the existing warning system requirements.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam4786OpenMr. Gerald F. Vinci Sun Refining and Marketing Company Tenn Penn Center 1801 Market St. Philadelphia, PA 19103-1699; Mr. Gerald F. Vinci Sun Refining and Marketing Company Tenn Penn Center 1801 Market St. Philadelphia PA 19103-1699; "Dear Mr. Vinci: This responds to your August 14, 1990 letter an telephone calls about your plans to convert the fuel system on a vehicle from gasoline to propane. You said your company ('Sun Refining') would like to purchase a new vehicle and convert it for purposes of your own research, and will not be reselling the vehicle. You ask about the requirements that would apply to the conversion. We do not have any requirements that would apply to the conversion if the conversion is made by Sun itself. The National Traffic and Motor Vehicle Safety Act and NHTSA's regulations generally do not apply to a vehicle after the vehicle is sold to a consumer (e.g., Sun) for purposes other than resale. Although the Act prohibits certain entities from tampering with or removing federally required safety features, the prohibition does not apply to modifications by a vehicle owner to his or her own vehicle. However, in the event you have the conversion done by a party other than your company, Federal law may apply. Section 108(a)(2)(A) of the Safety Act prohibits vehicle manufacturers, distributors, dealers and repair businesses from knowingly rendering inoperative federally required safety features when modifying a vehicle. I have enclosed an information sheet that discusses the application of 108(a)(2)(A) to fuel system conversions. NHTSA wishes to learn more about the safety of propane fuel systems and is considering a public announcement seeking information on various safety issues. We would, therefore, be interested in the results of your research when they're completed. Even though your conversion would not be covered by the FMVSS's, we suggest you consult State law to see if the State has requirements for propane vehicles. In addition, other Federal agencies may have regulations for your vehicle. If your vehicle would be a commercial vehicle, the regulations of the Federal Highway Administration (FHWA) may apply. I have forwarded a copy of your letter to FHWA for their reply. You might also contact the Environmental Protection Agency (EPA) for information about the conversion. EPA's general telephone number is (202) 382-2090. I hope this information is helpful. Please contact us if you have further questions. Sincerely, Paul Jackson Rice Chief Counsel Enclosure"; |
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ID: aiam3043OpenMr. Robert B. Kurre, Director of Engineering, Wayne Corporation, Industries Road, Post Office Box 1447, Richmond, IN 47374; Mr. Robert B. Kurre Director of Engineering Wayne Corporation Industries Road Post Office Box 1447 Richmond IN 47374; Dear Mr. Kurre: This responds to your June 11, 1979, letter asking whether sid push-out window exits in school buses installed pursuant to State requirements must be marked in accordance with the emergency exit requirements of S5.5.3 of Standard No. 217, *Bus Window Retention and Release*. In particular, you want to know whether these additional exits must be labeled on the bus exterior.; Section S5.5.3 of the standard requires that '[e]ach school bu emergency exit provided in accordance with S5.2.3.1 shall have the designation....on both the inside and outside surfaces of the bus. Section S5.2.3.1, in turn, requires that school buses be equipped with a rear emergency door or a side emergency door and a rear push-out window. Taken together, these two sections require that the required rear or side emergency door or rear push-out window must be appropriately marked on the inside and outside of the bus.; As the agency has frequently stated, all exits installed in schoo buses beyond those required by S5.2.3.1 need not comply with the exit requirements applicable to school bus exits. All additional exits must comply, however, with the other sections of the standard applicable to non-school buses. In this case, the additional exits would be required to be labeled in accordance with Sections S5.5.1 and S5.5.2 of the standard. Neither of these paragraphs requires the exit to be marked on the bus exterior.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1584OpenMr. Bruce Ladson, Assistant Division Manager, Universal Tire, 14622 Southlawn Lane, Rockville, MD 20850; Mr. Bruce Ladson Assistant Division Manager Universal Tire 14622 Southlawn Lane Rockville MD 20850; Dear Mr. Ladson: This is in response to your letter of August 6, 1974, asking wha registration procedures apply to tires manufactured before May 22, 1971, but sold after that date.; We interpret Part 574 of the Code of Federal Regulations, whic establishes the tire registration requirements, as applying only to tires manufactured after the effective date of the regulation, May 22, 1971. Therefore, tires manufactured before that date need not be registered.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam3297OpenMr. Ralph F. Lundregan, Government Relations Manager, Avery International, Specialty Materials Division, 50-L Edwards Ferry Road, Leesburg, VA 22075; Mr. Ralph F. Lundregan Government Relations Manager Avery International Specialty Materials Division 50-L Edwards Ferry Road Leesburg VA 22075; Dear Mr. Lundregan: This is in reply to your letter of April 16, 1980, asking whether Moto Vehicle Safety Standard No. 108 allows 'reflective markings (such as red diagonal stripes on a white reflective background) [to] be used to increase visibility on the front of [trucks and heavy vehicles]'.; You are correct that Standard No. 108 does not directly address thi question. The section of the standard that appears most pertinent to it, however, is S4.1.3 prohibiting the installation as original equipment of any reflective device 'that impairs the effectiveness of lighting equipment required by' Standard No. 108. We would be concerned, for example, if reflective materials were installed in a manner that might cause confusion with headlamps or front turn signal lamps. We also wish to point out that under the standard the use of the color red is at the rear of motor vehicles and that its appearance in any other location might also cause confusion.; However, as a practical matter the use of reflective materials as truc and heavy vehicle equipment sold either as original equipment or in the aftermarket is governed by requirements of the Bureau of Motor Carrier Safety (Federal Highway Administration) which prohibit use of the color red on the front of a vehicle. You should review their requirements before proceeding with your marketing plans. (49 CFR 393.26(e)(4)).; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam4552OpenMr. Garry Gallagher Vice President Metzeler Motorcycle Tire 4520 107th SW Everett, WA 98204; Mr. Garry Gallagher Vice President Metzeler Motorcycle Tire 4520 107th SW Everett WA 98204; "Dear Mr. Gallagher: This responds to your letter seeking a interpretation of Standard No. 119, New Pneumatic Tires for Motor Vehicles Other Than Passenger Cars (49 CFR /571.119). More specifically, you asked whether the letter 'B' must appear as part of the size designation of a motorcycle tire if that tire is of bias belted construction. The answer to your question is no. As you noted in your letter, section S6.5 of Standard No. 119 sets forth the marking requirements for tires used on motor vehicles other than passenger cars, including tires for use on motorcycles. Subsection S6.5(c) states that each such tire shall be marked with 'The tire size designation as listed in the documents and publications designated in S5.1.' Section S5.1, in turn, specifies tire and rim matching information that must be provided to the public. Generally speaking, the size designation of a tire shows only the physical dimensions of that tire, not necessarily its construction. Thus, the common meaning of the term 'size designation' does not necessarily include an indication of the tire's construction type. Further, no provision of Standard No. 119 requires a tire's size designation to indicate the tire's construction type. The only reference in section S6.5 of Standard No. 119 to a tire's construction type is in subsection S6.5(i), which requires the word 'radial' to appear on the tire's sidewall if the tire is of radial construction. Therefore, in response to your question, Standard No. 119 does not require the letter 'B' to be included in the size designation of bias belted motorcycle tires. You noted that your company sometimes adds the letter 'B' to the size designation of these tires as an internal code. NHTSA has long said that manufacturers are free to include additional information on the sidewall of their tires, provided that the additional information does not obscure or confuse the meaning of the required information, or otherwise defeat the purpose of the required information. In this case, the addition of the letter 'B' to the size designation would not appear to confuse or obscure the meaning of the size designation. Hence, there would be no apparent violation of Standard No. 119 by including the letter 'B' in the size designation of bias belted motorcycle tires. If you have any further questions or need additional information on this subject, please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992. Sincerely, Erika Z. Jones Chief Counsel"; |
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ID: aiam1750OpenHonorable John B. Anderson, House of Representatives, Washington, DC 20515; Honorable John B. Anderson House of Representatives Washington DC 20515; Dear Mr. Anderson: This responds to your request for consideration of Mr. George H Dobson's December 27, 1974, request for reconsideration of Standard No. 121, *Air brake systems*, because of its costs.; Standard No. 121 requires that newly-manufactured air-braked vehicle stop from speeds of up to 60 mph on wet and dry surfaces in the loaded and unloaded condition, without leaving a 12-foot-wide lane and without lockup of wheels above 10 mph. These performance requirements are based on a safety need for improved braking performance on air brake- equipped highway vehicles. Controlled stopping within the traffic lane is particularly important to tractor-trailer combinations to avoid 'jackknife' skids. The incompatibility of vehicle sizes can be reduced significantly by establishing equal stopping distances for trucks and passenger cars.; We have analyzed the costs and benefits to be gained in upgradin truck, bus, and trailer braking performance and have concluded that the savings in lives, injury, and property damage justify the incremental costs of this standard. Standard 121 does not require retrofit of vehicles manufactured prior to the standard's effective date.; From a cost standpoint, it is noteworthy that the arguments fo increased weight limits for commercial vehicles relied, in part, on the increased braking performance of vehicles which meet Standard No. 121. A major reason for the heavier vehicles would be to reduce the costs of transportation, and Standard No. 121 contributes directly to that goal.; As you may be aware, the NHTSA has in fact proposed postponement of th standard due to the current economic situation. Based on several hundred comments, there was persuasive evidence that a delay at this late date would create far greater dislocation in the automotive industry than would a January 1, 1975, implementation. A copy of our decision not to postpone the standard is enclosed.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam0842OpenMr. Richard Stevens, Cody Chevrolet, Inc. Barre-Montpelier Road, Montpelier, VT 05602; Mr. Richard Stevens Cody Chevrolet Inc. Barre-Montpelier Road Montpelier VT 05602; Dear Mr. Stevens: This is in reply to your letter of August 1, 1972, to the attention o Mr. Jerome Palisi of our White Plains, New York Office, concerning certification requirements for a vehicle which you describe and indicate will be used by a college to transport ball teams and school personnel, but will not be equipped with flashing lights or other special school bus equipment. You apparently wish to know whether you must consider this vehicle as a school bus for purposes of certification to Federal requirements.; 'School bus' is defined in the motor vehicle safety standards to mean bus 'designed primarily to carry children to and from school, but not including buses operated by common carriers in urban transportation of school children' (49 CFR 571.3). Based upon the description you provide, the NHTSA would not consider the vehicle you describe to be a school bus. For purposes of certification to Federal requirements (49 CFR Parts 567 and 568), there, 'gross vehicle weight rating' should not be computer under the minimum values specified for school buses. In addition, the requirement that vehicle type be inserted on the certification label should be met in inserting, 'BUS.'; This letter should not be construed to mean that the NHTSA takes position as to whether this vehicle need, under State law, conform to requirements for school buses. The State must determine the scope and application of its own laws.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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Request an Interpretation
You may email your request to Interpretations.NHTSA@dot.gov or send your request in hard copy to:
The Chief Counsel
National Highway Traffic Safety Administration, W41-326
U.S. Department of Transportation
1200 New Jersey Avenue SE
Washington, DC 20590
If you want to talk to someone at NHTSA about what a request for interpretation should include, call the Office of the Chief Counsel at 202-366-2992.
Please note that NHTSA’s response will be made available in this online database, and that the incoming interpretation request may also be made publicly available.