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
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ID: aiam5538OpenMr. Valter Sforca 84 Thomas Street Newark, NJ 07114; Mr. Valter Sforca 84 Thomas Street Newark NJ 07114; Dear Mr. Sforca: This is in reply to your letter of April 20, 1995 asking if there is a regulation that applies to the importation of an 'air equalizer for tire pressure.' Although you have not described your device, there are no Federal motor vehicle safety standards that apply to equipment installed in motor vehicles that regulate the air pressure of tires. If you are asked by the U.S. Customs Service to execute an HS-7 Declaration Form at the port of entry, you may check Box 1, declaring that the equipment was manufactured on a date when no applicable Federal motor vehicle safety standard was in effect. Because this device is motor vehicle equipment, and because you apparently would be its importer, you would be responsible for notifying buyers and recalling it if either you or we decided that it contained a safety related defect. We don't understand your phrase 'the system have a safety valve for the air brakes the truck, for a properly stop'. However, if the 'air equalizer' is installed by a manufacturer, distributor, dealer, or motor vehicle repair business, that person must not knowingly make inoperative any part of a truck's air brake system by installing the air equalizer. I am enclosing a copy of a letter concerning what appears to be a similar device, which will explain this more fully. If you have any further questions, you may refer them to Taylor Vinson of this Office, with whom you spoke previously (202-366-5263). Sincerely, John Womack Acting Chief Counsel Enclosure; |
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ID: aiam2707OpenMr. Timothy Paul Barton, Anders-Barton Automotive Design, 10770 Lower Azusa Road, El Monte, CA 91713; Mr. Timothy Paul Barton Anders-Barton Automotive Design 10770 Lower Azusa Road El Monte CA 91713; Dear Mr. Barton: This responds to your letter asking whether your modifications o Toyota pickup trucks comply with the requirements of the National Highway Traffic Safety Administration (NHTSA).; The NHTSA requires that a person who modifies a vehicle attach a labe to the vehicle indicating that, as modified, the vehicle continues to comply with all safety standards (49 CFR Part 567, *Certification). From your letter, it appears that you are in compliance with this requirement. You should note further that section 108(a)(2)(A) of the National Traffic and Motor Vehicle Safety Act of 1966 (15 U.S.C. 1381 *et seq*.) prohibits a manufacturer, distributor, dealer, or Motor vehicle repair business from rendering inoperative any device or element of design installed in a motor vehicle or an item of motor vehicle equipment in compliance with a Federal safety standards. In the case of a vehicle which is being converted from one vehicle type to another (e.g., a sedan to a convertible), modification of safety systems would not violate section 108 as long as the modified systems complied with the standards that would have been applicable to the vehicle had it been originally manufactured as the vehicle type to which it is being converted.; As long as you ensure that the vehicle continues to comply with all o the standards applicable to it and you do not render inoperative any safety device or element of design, you would appear to be in compliance with the agency's requirements. You should note that the waiver signed by your customers would not remove your responsibility for any defects or noncompliances with our standards.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam3815OpenMr. H. Nakaya, Branch Manager, Mazda (North America), Inc., Suite 462, 23777 Greenfield Road, Southfield, Michigan 48075; Mr. H. Nakaya Branch Manager Mazda (North America) Inc. Suite 462 23777 Greenfield Road Southfield Michigan 48075; Dear Mr. Nakaya: This responds to your letter of January 20, 1984, requesting a interpretation of Federal Motor Vehicle Safety Standard (FMVSS) No. 102, *Transmission Shift Lever Sequence, Starter Interlock, and Transmission Braking Effect*. You asked whether Mazda may modify the display of shift lever positions for vehicles equipped with automatic transmissions to delete the gear lever indicator. As explained below, FMVSS No. 102 does not permit the deletion of the gear position indicator.; You should be aware that the National Highway Traffic Safet Administration (NHTSA) does not pass approval on the compliance of any vehicle or equipment with a safety standard before the actual events that underlie certification. Under the Vehicle Safety Act, it is the manufacturer's responsibility to determine whether its vehicles and equipment comply with all applicable safety standards and regulations, and to certify its products in accordance with that determination. Therefore, the following statements only represents the agency's opinion based on the information provided in your letter.; Your letter states that Mazda automobiles with automatic transmission currently display the gear lever sequence and identify the shift lever position of the automobile. Based on the information in your letter, the agency understands that you propose to modify the display in such a way that '[t]he actual gear selection would not be indicated (as is the case of current manual transmissions).' The pattern of the gear positions would be embossed either on the instrument panel or on the shift lever handle.; Paragraph S3.2. of Federal Motor Vehicle Safety Standard No. 102 stat that the '[i]dentification of shift lever *positions* of automatic transmissions...shall be permanently displayed in view of the driver.' [Emphasis added.] 49 CFR S571.102. NHTSA interprets 'position' to mean the position of the gears in relation to each other *and* the position that the driver has selected at the time of selection. Therefore, the display of a gear lever sequence and a gear position indicator is required for automobiles equipped with automatic transmissions.; You should note that FMVSS No. 101, *Controls and Displays,* als applies to the display of automatic gar positions. Paragraph S5 of the standard requires that, inter alia, each passenger car, multipurpose passenger vehicle, truck or bus less than 10,000 pounds GVWR with any display listed in S5.1 or in column 1 of Table 2 of the standard shall meet the requirements for the location, identification, and illumination of such display. Since 'gear position' is listed under S5.1, and 'Automatic Gear Position' is listed under Table 2, the requirements of FMVSS No. 101 apply to the display of shift lever positions in vehicles equipped with automatic transmissions.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1828OpenMr. C. Henderson, Director of Engineering, American Safety Equipment Corporation, 500 Library Street, San Fernando, CA 91340; Mr. C. Henderson Director of Engineering American Safety Equipment Corporation 500 Library Street San Fernando CA 91340; Dear Mr. Henderson: This is in reply to your letter of January 22, 1975, which formall petitioned for a change to Federal Motor Vehicle Safety Standard No. 213, Child Seating Systems. Your petition requested an exception to the padding requirement for hardware which serves as a torso load distribution pad and which is attached only to the child seat belt system.; Based on a further review of your design, we have reconsidered th position stated in our December 20, 1974, letter to you. We now consider this device to be belt adjustment hardware, even though it is also used to distribute loads, and have determined that no padding is therefore required. We consider that the safety of your child seat would not be appreciably improved by padding this torso load distribution pad. This is further confirmed by the primate test films and data which you presented to us in our meeting of January 21, 1975. We would suggest that this item, nonetheless, provide a radius in accordance with S4.10.1(a).; We presume that this interpretation will eliminate the need for formal response to your petition. If that is the case we would appreciate a letter from you to that effect.; Sincerely, James C. Schultz, Chief Counsel |
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ID: aiam5168OpenMr. John B. White Industry Standards & Government Regulations Michelin Post Office Box 2501 Greenville, SC 29602; Mr. John B. White Industry Standards & Government Regulations Michelin Post Office Box 2501 Greenville SC 29602; "Dear Mr. White: This responds to your letter asking the Nationa Highway Traffic Safety Administration (NHTSA) to clarify our certification procedures for the information of some of your customers. Specifically, you stated that some customers believe that you are required to test your tires for compliance with the Federal motor vehicle safety standards (FMVSS) and the Uniform Tire Quality Grading Standards (UTQGS), and that this agency then certifies your tires after reviewing and evaluating your test results. Those impressions are incorrect. All new tires sold in the United States for use on passenger cars must be certified by the manufacturer as complying with FMVSS 109, New pneumatic tires, found at 49 CFR 571.109, while all new tires sold for use on motor vehicles other than passenger cars must be certified as complying with FMVSS 119, New pneumatic tires for vehicles other than passenger cars, found at 49 CFR 571.119. The National Traffic and Motor Vehicle Safety Act, 15 U.S.C. 1381, et seq. (Safety Act) establishes a self-certification procedure applicable to new motor vehicles and new items of motor vehicle equipment, which includes tires. This means that the tire manufacturer, and not a governmental agency such as NHTSA, certifies that its tires comply with applicable FMVSSs. Each new tire must be certified as meeting the applicable FMVSSs regardless of whether the tire meets an equal or higher standard in another country. The UTQGS are set forth in 49 CFR 575.104. Those standards do not require certification in the same manner as the FMVSSs. The UTQGS require that manufacturers mold onto or into the sidewalls of their tires the comparative ratings of those tires for treadwear, traction, and temperature resistance for the use and benefit of consumers. Again, that is the manufacturers' responsibility and NHTSA neither reviews nor approves the ratings prior to their assignments by the manufacturers. Neither the Safety Act nor NHTSA standards and regulations require that a manufacturer base its certifications on any specific tests, any number of specified tests or, for that matter, any tests at all. A manufacturer is only required to exercise due care in certifying its tires. It is the responsibility of each tire manufacturer to determine initially what test results, computer simulations, engineering analyses, or other information it needs to enable it to certify that its tires comply with applicable Federal safety standards. Once a manufacturer has determined that its tires meet all applicable Federal safety standards, it certifies such compliance by molding the letters 'DOT' onto at least one sidewall of each certified tire. If manufacturers conduct any tests, they are not required by Federal law or regulation to release their test results to the public. This agency does not perform any pre-sale testing, approval, or certification of tires, whether of foreign or domestic manufacture, before introduction into the U. S. retail market. Similarly, NHTSA does not approve or certify manufacturers' test results. Rather, NHTSA randomly tests certified tires to determine whether the tires do, in fact, comply with applicable standards. For such enforcement checks, NHTSA purchases tires 'off the shelf' from retail tire dealers and tests those tires according to the procedures specified in the standards. If the tires pass the tests, no further action is taken. If they fail the tests and are determined not to comply with any applicable standard or standards, the manufacturer is responsible for recalling the tires and remedying the noncompliance without charge to the consumer. Government compliance test results are available to the public upon request from the NHTSA Technical Reference Division (NAD 52), 400 Seventh Street SW, Room 5108, Washington, D.C. 20590, (202) 366-2768. I hope this information will assist you in clarifying tire certification requirements to the satisfaction of your customers. If you have any further questions or desire further clarification, please feel free to contact Walter Myers of my staff at this address or at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam0690OpenMr. J. Hunter, Deputy Group Chief Technologist, British Vita Company Limited, Middleton, Manchester, England; Mr. J. Hunter Deputy Group Chief Technologist British Vita Company Limited Middleton Manchester England; Dear Mr. Hunter: This is in reply to your letter of April 14, 1972, requesting a interpretation as to how 'Cavitex Latex Foam' should be tested for conformity to Motor Vehicle Safety Standard No. 302, 'Flammability of Interior Materials.' You enclose two drawings illustrating this material, which show that the 14 x 4-inch specimen will contain cavities running from the underside of the material to within 1/2- inch from the top surface of the material. You ask whether the sample to be used for testing pursuant to S5.2.1 of the standard should be cut from the top or bottom of the specimen, and which side of the sample should be exposed to the flame. Your letter indicates that the side of the cushion containing the cavity openings faces the floor of the vehicle, and a continuous flat surface faces the occupant compartment.; We will consider you to have followed the test procedure of S5. of th standard if the 1/2- inch thick test sample is cut from that part of the material nearest to the occupant compartment, and if the surface of that sample exposed to the flame is that which is also closest to the occupant compartment. According to your drawings, you should therefore test a specimen cut from the 'upper face' of the material with the flat surface of that specimen exposed to the flame in the test cabinet.; We thank you for your compliments. Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1982OpenMr. Byron A. Crampton, Manager of Engineering Services, Truck Body and Equipment Association, Inc., 5530 Wisconsin Ave., Suite 1220, Washington, DC 20015; Mr. Byron A. Crampton Manager of Engineering Services Truck Body and Equipment Association Inc. 5530 Wisconsin Ave. Suite 1220 Washington DC 20015; Dear Mr. Crampton:#This is in response to your letter of July 3, 1975 forwarding a copy of an earlier letter that evidently was never received by us. You asked whether a garbage truck that contained an auxiliary driver's position on the right side of the vehicle, with a separate set of controls, needs to have a seat at the auxiliary position, and whether access to such controls as the heater, wipers, and lights from this position is required.#We consider the standards relating to the driver's position as relating to the normal position, and not to an auxiliary driving position. The answer is no, therefore, to both of the above questions.#Yours truly, Richard B. Dyson, Assistant Chief Counsel; |
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ID: aiam5492OpenMr. Scott E. Peters Director, Regulations & Compliance U.S. Electricar 5355 Skylane Boulevard Santa Rosa, CA 95403; Mr. Scott E. Peters Director Regulations & Compliance U.S. Electricar 5355 Skylane Boulevard Santa Rosa CA 95403; "Dear Mr. Peters: This responds to your letter to me in which you aske whether Federal Motor Vehicle Safety Standard (FMVSS) No. 110, Tire selection and rims (49 CFR 571.110), applies to your Electricar sedan. You explained that your Electricar sedan (Electricar), a converted Geo Prizm, is being built under NHTSA Exemption No. 92-3 for low-emission vehicles. You stated that the Electricar's speed and endurance limitations are substantially below those of internal combustion-powered vehicles. You further stated that it is your understanding that 'the purpose of Standard No. 110, S4.4.2 (I assume you meant paragraph S4.2.2, since there is no S4.4.2 in the standard) is to ensure against tire failure due to prolonged operation at speeds in the range of 75 mph or higher.' Thus, you interpret FMVSS No. 110 as not applying to the Electricar or other electric passenger cars 'in which it is physically impossible to operate at high speeds for an extended duration.' You asked this agency, therefore, to review paragraph S4.2.2 and provide you our opinion as to its applicability to your Electricar. As discussed below, the requirements of S4.2.2 are applicable to electric passenger cars. By way of background information, the National Highway Traffic Safety Administration issues safety standards for motor vehicles and motor vehicle equipment. The agency does not provide approvals of motor vehicles or motor vehicle equipment. Instead, manufacturers are required to certify that their vehicles and equipment meet applicable safety standards. Federal Motor Vehicle Safety Standard No. 110 specifies requirements for tire selection to prevent overloading. Section S2 of the standard provides that the standard applies to passenger cars. S4.2 of the standard specifies the following tire load limits: S4.2.1 The vehicle maximum load on the tire shall not be greater than the applicable maximum load rating as marked on the sidewall of the tire. S4.2.2 The vehicle normal load on the tire shall not be greater than the test load used in the high speed performance test specified in S5.5 of section 571.109 of that tire. The test load used in the high speed performance test specified in S5.5 of Standard No. 109 is 88 percent of the tire's maximum load rating as marked on the tire sidewall. With respect to your question whether S4.2.2 applies to electric passenger cars, the answer is yes. That section applies on its face to all passenger cars, and does not include an exception for electric passenger cars. Your understanding that the purpose of S4.2.2 is limited to ensuring against tire failure due to prolonged operation at speeds in the range of 75 mph or higher is incorrect. The reference in that requirement to Standard No. 109's high speed performance test is for the sole purpose of specifying a load and not to indicate that the requirement is limited to high speed operation. As indicated above, Standard No. 110 seeks to ensure that tires are not overloaded. One way Standard No. 110 does this is by requiring in S4.2.1 that the vehicle maximum load on the tire not exceed the maximum load rating of the tire. Another way Standard No. 110 does this is by limiting the vehicle normal load on the tire, so that the tire will have some reserve load carrying capacity available to handle safely cargo and other kinds of added loading the car may experience. S4.2.2 does this by limiting the normal load on a tire to 88 percent of the tire's maximum load rating, which ensures that 12 percent of the tire's load rating will be available to bear cargo and other added loads. I hope this information is helpful to you. Should you have any further questions or need additional information, please feel free to contact Walter Myers of my staff at this address or at (202) 366-2992. Sincerely, Philip R. Recht Chief Counsel Enclosure"; |
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ID: aiam2357OpenRoderick H. Willcox, Esq., Messrs. Chester, Hoffman, Park, Willcox, & Rose, 16 East Broad Street, Columbus, OH, 43215; Roderick H. Willcox Esq. Messrs. Chester Hoffman Park Willcox & Rose 16 East Broad Street Columbus OH 43215; >>> Re: W.B. Marvin Manufacturing Co.<<< Dear Mr. Willcox: This is in reply to your letter of June 16, 1976, asking severa questions with respect to the applicability of 15 USC 1397(a)(2)(A) of the National Traffic and Motor Vehicle Safety Act and Federal Motor Vehicle Safety Standard No. 108 (49 CFR 571.108) to a product manufactured by your client, the W.B. Marvin Manufacturing Company. This product is 'a screen which fits on the front part of the automobile and protects the radiator, headlamps and other lower parts of the car' from bugs.; W.B. Marvin would not be in violation of either the Act or Standard No 108 by manufacturing and selling these screens. Such liability as may exist centers on the installation of them. Standard No. 108 establishes requirements for lighting equipment on new motor vehicles, and for replacement equipment. One of the requirements of SAE Standard J580a, *Sealed Beam Headlamp*, June 1966, incorporated by reference in Standard No. 108, is that ' a headlamp, when in use, shall not have any styling or other feature, such as a glass cover or grille in front of the lens.' Since the screen is positioned in front of the headlamps it would be an 'other feature' of the type intended to be prohibited by the standard if, as appears likely, it affects compliance with headlamp photometrics (SAE Standard J579) or headlamp aim (SAE Standard J580). If installation results in a noncompliance, the screen could not, therefore, be legally installed by a vehicle manufacturer, distributor, or dealer as original equipment on a motor vehicle.; As for replacement equipment, under Section 1397 (a)(2)(A) of the Ac an automobile owner may himself modify his vehicle in any manner he chooses, but modifications performed at his request by others may not 'render inoperative in whole or part, any device or element of design installed on . . . a motor vehicle . . . in compliance with an applicable Federal motor vehicle safety standard.' If installation of the screen affects compliance with headlamp photometrics or other requirements, then it would appear to 'render inoperative' a lighting device installed in accordance with a Federal motor vehicle safety standard, within the meaning of Section 1397(a)(2)(A). Installation by the auto service center of the retailer would therefore be prohibited, since such a facility is deemed a 'motor vehicle repair business.'; There are no Federal motor vehicle safety standards that directly appl to the screen as an item of motor vehicle equipment, nor do I know of any other Federal regulation affecting it.; I hope this letter is responsive to your questions. Yours truly, Frank Berndt, Acting Chief Counsel |
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ID: aiam2642OpenMr. Robert Rubenstein, Chief Engineer, Alderson Research Laboratories, Inc., 390 Ludlow Street, Stamford, CT 06904; Mr. Robert Rubenstein Chief Engineer Alderson Research Laboratories Inc. 390 Ludlow Street Stamford CT 06904; Dear Mr. Rubinstein (sic): This responds to Alderson Research Laboratory's July 15, 1977, reques for confirmation that Part 572, *Anthropomorphic Test Dummy* (49 CFR 572), neither requires nor prohibits venting of the abdominal insert specified in drawing No. ATD 3250-2. The agency proposed the addition of leak test specifications to the drawing in August 1975 (40 CFR 33462, August 5, 1975) but they were not made final (42 CFR 7148, February 7, 1977).; Your interpretation that Part 572 neither requires nor prohibit venting of the abdominal insert is correct. The language you cite from the preamble to our February 1977 rulemaking is misleading in suggesting the requirement for venting. The agency more clearly described the requirement in its most recent amendment of Part 572 (42 FR 34299, July 5, 1977), stating that the Part does not 'specify an abdominal sealing specification.' Agency testing demonstrated conforming results both with and without venting (DOT HS-020875) and sees no reason to control this aspect of dummy design.; Sincerely, Joseph J. Levin, Jr., 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.