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: aiam2152OpenMr. Charles J. Calvin, President, Truck Trailer Manufacturer Association, 2430 Pennsylvania Avenue, N.W., Washington, DC 20037; Mr. Charles J. Calvin President Truck Trailer Manufacturer Association 2430 Pennsylvania Avenue N.W. Washington DC 20037; Dear Mr. Calvin: This responds to the Truck Trailer Manufacturer Association's Novembe 17, 1975, request that the NHTSA reconsider its opinion that modification of existing tank trailers to increase their volumetric capacity and length does not constitute manufacture of a new air-braked trailer that must comply with Standard No. 121, *Air Brake Systems*. This opinion appears in a letter of August 28, 1975, to Stainless Tank and Equipment, Inc.; The National Traffic and Motor Vehicle Safety Act (the Act) authorize the issuance of motor vehicle safety standards (15 U.S.C. S 1392(a)) and prohibits, among other things, the manufacture of a motor vehicle on or after the date any applicable standard takes effect unless the vehicle conforms to the standard, and is so certified (15 U.S.C. S 1397(a)(1)(A), 1403). With the 1974 Amendments, (15 U.S.C. S 1397(a)(2)(A)) no manufacturer, distributor, dealer, or repair business may perform modifications that render inoperative any device or element of design required by a standard. However, unless the modifications performed are so extensive as to constitute legally the manufacture of a new vehicle, the standards that continue to apply to a vehicle are those in effect at the time of its original manufacture, not those that may have come into effect at a later date.; The modification of a tank trailer to increase its volumetric capacit and length does not, in our view, constitute the manufacture of a new vehicle in the typical situation (about an 18-inch increase in length). For this reason, Standard No. 121 does not apply to existing vehicles that are modified in accordance with your description.; This response does not address the issue of compliance with Federa motor carrier regulations raised in your November 17, 1975, letter.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam0624OpenStephen F. Hefner, Esq., Nance, Caston, Hefner and Green, Attorneys at Law, 421 North Crockett Street, Sherman, TX 75090; Stephen F. Hefner Esq. Nance Caston Hefner and Green Attorneys at Law 421 North Crockett Street Sherman TX 75090; Dear Mr. Hefner: This is in reply to your letter of January 25, 1972, concerning th certification of new trailers which your client manufactures. You state that some of these trailers are shipped (to customers) equipped with used tires that are intended primarily to be used to ship the trailers to their destination, and ask whether these tires should be taken into account in the values for GVWR and GAWR on the certification label.; We do not consider that temporary tires attached to a vehicle fo purposes of shipment should be reflected in the GVWR and GAWR on the certification label, if these tires are not intended to be part of the completed vehicle. consequently, we would expect trailers shipped with such tires to be treated similarly for purposes of certification as vehicles for which no tires have been provided. In such a case, the complete vehicle manufacturer, as indicated in the preamble to the Certification regulations (April 14, 1971, 36 F.R. 2054) must still bear responsibility and certify the vehicle, even though he does not install the tires with which the vehicle will ultimately be equipped. We suggest that one manner in which this could be accomplished by the manufacturer is to list GAWR and GVWR for the optional tire sizes which he recommends in accordance with the amendment to the Certification regulations published December 10, 1971 (35 F.R. 23571). The manufacturer should make it clear to the purchaser of the vehicle that the temporary tires should be replaced when the vehicle is put into use.; We are pleased to be of assistance. Sincerely, Francis Armstrong, Director, Office of Standard Enforcement, Motor Vehicle Programs; |
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ID: aiam0625OpenStephen F. Hefner, Esq., Nance, Caston, Hefner and Green, Attorneys at Law, 421 North Crockett Street, Sherman, TX 75090; Stephen F. Hefner Esq. Nance Caston Hefner and Green Attorneys at Law 421 North Crockett Street Sherman TX 75090; Dear Mr. Hefner: This is in reply to your letter of January 25, 1972, concerning th certification of new trailers which your client manufactures. You state that some of these trailers are shipped (to customers) equipped with used tires that are intended primarily to be used to ship the trailers to their destination, and ask whether these tires should be taken into account in the values for GVWR and GAWR on the certification label.; We do not consider that temporary tires attached to a vehicle fo purposes of shipment should be reflected in the GVWR and GAWR on the certification label, if these tires are not intended to be part of the completed vehicle. consequently, we would expect trailers shipped with such tires to be treated similarly for purposes of certification as vehicles for which no tires have been provided. In such a case, the complete vehicle manufacturer, as indicated in the preamble to the Certification regulations (April 14, 1971, 36 F.R. 2054) must still bear responsibility and certify the vehicle, even though he does not install the tires with which the vehicle will ultimately be equipped. We suggest that one manner in which this could be accomplished by the manufacturer is to list GAWR and GVWR for the optional tire sizes which he recommends in accordance with the amendment to the Certification regulations published December 10, 1971 (35 F.R. 23571). The manufacturer should make it clear to the purchaser of the vehicle that the temporary tires should be replaced when the vehicle is put into use.; We are pleased to be of assistance. Sincerely, Francis Armstrong, Director, Office of Standard Enforcement, Motor Vehicle Programs; |
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ID: aiam0187OpenMr. E. W. Bernitt, Vice President, Safety and Quality Assurance, American Motors Corporation, 14250 Plymouth Road, Detroit, MI 48232; Mr. E. W. Bernitt Vice President Safety and Quality Assurance American Motors Corporation 14250 Plymouth Road Detroit MI 48232; Dear Mr. Bernitt: We have received your submittal of consumer information in response t the requirements of 49 CFR Part 375. That regulation requires that manufacturers submit their information to the Administrator 30 days in advance of the time it is made available to prospective purchasers. Since we have not required that this advance submittal be in the same form as that given to prospective purchasers, the following comments are only advisory in nature. There are several respects, however, in which your information, if supplied in this form to prospective or actual purchasers, would not satisfy the requirements of the regulations.; >>>1. The Stopping Distance information is presented as a 'range o stopping distances,' both in numerical and graphical form. The regulations clearly require a single stopping distance figure to be provided for a given group, that can be met or exceeded by all vehicles in the group. We do not know, and consumers surely would not know, the significance of the lower figure given. Even if it were clear, the provision of such additional, non-required information in close proximity to the required data would cause confusion in attempting to compare figures between various makes--the main purpose of the information.; 2. The provision of four sets of data in respect to partial failure o the braking system, for 'fronts operative' and 'rears operative,' and for lightly-loaded and maximum-loaded vehicles, is not in accordance with the regulation requirement that information be provided for the 'most adverse combination' of weights and system failures. As stated in item 1, above, the inserting of this additional information, self-serving in every case since only the worst element should be included, would make comparisons difficult and be unfair to competing manufacturers who followed the regulations strictly.; 3. The form of the Stopping Distance information would fail to satisf the requirement that the information be presented 'in essentially the form illustrated in Figure 1' of 49 CFR S 375.101. In particular, we refer to the placing of two columns side by side instead of the single-axis graph depicted in that figure, and the inclusion of other verbiage between the required statements and warnings and the information itself. The reference to shorter stopping distances with wheel lock-up and without restricting pedal effort, between the required information and the graphs, is especially objectionable, since the safety advantages of avoiding wheel skid were a particular concern in developing this regulation. Although the regulations do not prohibit the provision of other than required information in a Consumer Information booklet, they do require that it be separated in such a manner that the required information, both textual and quantitative, is presented in 'essentially the form illustrated.'; 4. The Tire Reserve Load section of the regulations requires that 'th table that is provided for a specific vehicle shall contain only information that is applicable to that vehicle.' This requirement prohibits a large, all-purpose chart such as yours, with information for many vehicles included on it, at least as far as the information given to the actual purchaser of a vehicle is concerned. More generally, the information is not presented in 'essentially the form illustrated in Figure 1' of 49 CFR S 375.102.; 5. The large, all-inclusive bar graph on Acceleration and Passin Ability does not present the information in 'essentially the form illustrated in Figure 1' of 49 CFR S 375.106, as required.<<<; We will be glad to answer any questions that you may have with respec to the requirements of these or other motor vehicle safety regulations and standards.; Sincerely, Robert Brenner, Acting Director |
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ID: aiam0189OpenMr. E. W. Bernitt, Vice President, Safety and Quality Assurance, American Motors Corporation, 14250 Plymouth Road, Detroit, MI 48232; Mr. E. W. Bernitt Vice President Safety and Quality Assurance American Motors Corporation 14250 Plymouth Road Detroit MI 48232; Dear Mr. Bernitt: We have received your submittal of consumer information in response t the requirements of 49 CFR Part 375. That regulation requires that manufacturers submit their information to the Administrator 30 days in advance of the time it is made available to prospective purchasers. Since we have not required that this advance submittal be in the same form as that given to prospective purchasers, the following comments are only advisory in nature. There are several respects, however, in which your information, if supplied in this form to prospective or actual purchasers, would not satisfy the requirements of the regulations.; >>>1. The Stopping Distance information is presented as a 'range o stopping distances,' both in numerical and graphical form. The regulations clearly require a single stopping distance figure to be provided for a given group, that can be met or exceeded by all vehicles in the group. We do not know, and consumers surely would not know, the significance of the lower figure given. Even if it were clear, the provision of such additional, non-required information in close proximity to the required data would cause confusion in attempting to compare figures between various makes--the main purpose of the information.; 2. The provision of four sets of data in respect to partial failure o the braking system, for 'fronts operative' and 'rears operative,' and for lightly-loaded and maximum-loaded vehicles, is not in accordance with the regulation requirement that information be provided for the 'most adverse combination' of weights and system failures. As stated in item 1, above, the inserting of this additional information, self-serving in every case since only the worst element should be included, would make comparisons difficult and be unfair to competing manufacturers who followed the regulations strictly.; 3. The form of the Stopping Distance information would fail to satisf the requirement that the information be presented 'in essentially the form illustrated in Figure 1' of 49 CFR S 375.101. In particular, we refer to the placing of two columns side by side instead of the single-axis graph depicted in that figure, and the inclusion of other verbiage between the required statements and warnings and the information itself. The reference to shorter stopping distances with wheel lock-up and without restricting pedal effort, between the required information and the graphs, is especially objectionable, since the safety advantages of avoiding wheel skid were a particular concern in developing this regulation. Although the regulations do not prohibit the provision of other than required information in a Consumer Information booklet, they do require that it be separated in such a manner that the required information, both textual and quantitative, is presented in 'essentially the form illustrated.'; 4. The Tire Reserve Load section of the regulations requires that 'th table that is provided for a specific vehicle shall contain only information that is applicable to that vehicle.' This requirement prohibits a large, all-purpose chart such as yours, with information for many vehicles included on it, at least as far as the information given to the actual purchaser of a vehicle is concerned. More generally, the information is not presented in 'essentially the form illustrated in Figure 1' of 49 CFR S 375.102.; 5. The large, all-inclusive bar graph on Acceleration and Passin Ability does not present the information in 'essentially the form illustrated in Figure 1' of 49 CFR S 375.106, as required.<<<; We will be glad to answer any questions that you may have with respec to the requirements of these or other motor vehicle safety regulations and standards.; Sincerely, Robert Brenner, Acting Director |
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ID: aiam5351OpenMr. Mark M. McGregor 7 Highfield Drive Sandwich, MA 02563; Mr. Mark M. McGregor 7 Highfield Drive Sandwich MA 02563; "Dear Mr. McGregor: This is in reply to your letter of March 31, 1994 with respect to Federal regulations that may apply to a motor vehicle rear lighting device that you have invented. Your 'Safe Driving Indicator Light', mounted on the rear of a vehicle, would emit one color ('possibly green') which would change to red when a vehicle following came too close. To put it at its simplest, an invention such as yours is permissible under the Federal statutes and regulations of this agency as long as it does not negatively affect the performance of the lighting equipment that is required by Federal Motor Vehicle Safety Standard No. 108 Lamps, Reflective Devices and Associated Equipment. This is the Federal standard that specifies what is required as original lighting equipment on motor vehicles. More specifically, paragraph S5.1.3 of Standard No. 108 permits non-required lighting devices as original equipment if it does not impair the effectiveness of the required lighting equipment. We believe that your invention, as described, has the potentiality to impair the stop lamp system. While running lamps of the color red are permitted (e.g. taillamps), the sudden change from green to red of the lamp of your system could be misinterpreted as a signal to the car following that the car ahead is preparing to stop. However, the purpose of your lamp is not to indicate a stop but to warn the following driver that (s)he is too close. As a warning lamp, we believe that your use of amber as a color, rather than red, would convey the desired message without impairing the effectiveness of the stop lamps. But you should consider the intensity and location of the lamps to avoid impairment of the rear turn signal lamps. With respect to the aftermarket, 15 U.S.C. 1397(a)(2)(A) (Section 108(a)(20(A) of the National Traffic and Motor Vehicle Safety Act) prohibits a manufacturer, dealer, distributor, or motor vehicle repair business from knowingly rendering inoperative in whole or in part any device or element of design installed in accordance with a Federal motor vehicle safety standard. We interpret this as not forbidding activities by persons other than those named above that affect the compliance of a vehicle with the Federal safety standards. Thus, the installation of your invention emitting a red color is not precluded if the invention is intended for installation by a vehicle owner, and is not prohibited for installation by others if the warning light color is amber. However, you must still determine whether use of the lamp is permissible under the laws of States where it will be used. We are unable to advise you on State laws and suggest that you write for an opinion to: American Association of Motor Vehicle Administrators, 4600 Wilson Boulevard, Arlington, Va. 22203. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam5567OpenJ. Gregory Studemeyer, Esq. 1804 Bull Street Post Office Box 12201 Columbia, SC 29211-2201; J. Gregory Studemeyer Esq. 1804 Bull Street Post Office Box 12201 Columbia SC 29211-2201; Dear Mr. Studemeyer: This responds to your letter of January 5, 1995 to this agency and your telephone conversation with Walter Myers of my staff on June 12, 1995, regarding the school bus standards we administer. You asked whether 'your agency or any other federal agency notifies educational institutions of these school bus requirements.' The answer is no. The National Highway Traffic Safety Administration (NHTSA) does not maintain data on all schools or school districts throughout the nation, and does not routinely communicate with individual schools or school districts. The agency does, however, attend and disseminate information at school bus meetings and conferences nationwide and publishes all changes in school bus requirements in the Federal Register. In addition, NHTSA works closely and frequently with state directors of pupil transportation with regard to school transportation matters. In South Carolina, that official is the Director, Office of Transportation, Department of Education, 1429 Senate Street, Room 512, Columbia, SC 29201. Their telephone number is (803) 734- 8244, and their fax number is (803) 734-8624. Also for your information please find enclosed a fact sheet prepared by this office summarizing Federal school bus safety requirements. If 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, John Womack Acting Chief Counsel Enclosure; |
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ID: aiam5248OpenMr. Terry Karas T.K. Auto Inc. 4116 Notre Dame Chomedey, Laval, Quebec H7w 1T1 Canada; Mr. Terry Karas T.K. Auto Inc. 4116 Notre Dame Chomedey Laval Quebec H7w 1T1 Canada; FAX 514-688-6968 Dear Mr. Karas: This responds to the concern you expressed by telephone to Taylor Vinson of this Office that a phrase in our letter of October 18, 1993, may be misinterpreted by the U.S. Customs Service. The final sentence of the paragraph that begins page 2 of that letter reads: 'If this examination indicates that the vehicle is Canadian, and if it is being imported for commercial purposes, then the vehicle is subject to the registered importer process.' In the context of the letter, we assumed that it was clear that the Canadian vehicle in question was one that did not comply with the U.S. Federal motor vehicle safety standards. You believe that Customs may interpret the word 'Canadian' to mean any vehicle of Canadian manufacture, whether or not complying with the U.S. safety standards. We are pleased to provide the following clarification. With reference to the examination of the Canadian-manufactured vehicle in question, if it indicates that the speedometer does not have mph markings, this will demonstrate that the certification is to Canadian standards. Consequently, the Canadian- manufactured vehicle is one that does not comply, and is not certified as complying, with the U.S. standards, and, if it is being imported for commercial purposes, is subject to entry under bond and the registered importer process. Sincerely, John Womack Acting Chief Counsel; |
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ID: aiam5183OpenMr. Steve Reeder President & General Manager Trails West Manufacturing P.O. Box 67 Preston, ID 83263; Mr. Steve Reeder President & General Manager Trails West Manufacturing P.O. Box 67 Preston ID 83263; Dear Mr. Reeder: This responds to your letter of April 21, 1993, t Taylor Vinson of this Office, in which you ask questions about the applicability of Federal Motor Vehicle Safety Standard No. 108 to the livestock trailers that you manufacture. The trailer box is 78 inches wide, but the overall vehicle width exceeds 80 inches when the fenders are added. You have asked whether such trailers must be equipped with lamps required of vehicles whose overall width is 80 inches or more (clearance and identification lamps) as they will be installed on the trailer box. In an interpretation published in l976 which remains valid today, the agency stated that 'overall width' refers to 'the nominal design dimension of the widest part of the vehicle . . . exclusive of flexible fender extensions, and mud flaps . . . .' The trailers you manufacture do not appear to be equipped with 'flexible fender extensions', according to the literature that you supplied, and therefore the fenders would be included in determining the overall width. Accordingly, they would be required to be equipped with clearance and identification lamps. Although the clearance lamps will be located on the box, they should be placed, as nearly as possible, to indicate the overall width of the vehicle and as near the top as practicable, as Table II of Standard No. 108 requires. Thus, to answer your second question, side marker lamps would be located as required by Table II rather than Table IV. In determining whether the overall length of the trailer is 30 feet or more for purposes of installation of intermediate side marker lamps and reflectors, you ask whether 'the gooseneck or 5th wheel portion of the trailer which extends over the tow vehicle' should be included. The agency has not adopted a definition of 'overall length.' However, with respect to a trailer that is less than 6 feet in overall length, paragraph S5.1.1.15 requires that 'the trailer tongue' be included in the measurement. Therefore we believe that the calculation of overall length for longer trailers should also include the trailer tongue or equivalent connector to the towing vehicle. You have also asked if 'front clearance lights would be required where the gooseneck or 5th wheel portion of the trailer extends over the tow vehicle.' The answer is yes. Table II of Standard No. 108 requires that amber clearance lamps be located 'on the front' and as near the top as practicable, which we interpret to be the foremost, highest part of the trailer. Your final question relates to regulations for 'safety chains' for your products. We are unaware of any Federal requirements that apply to this item of equipment. States may have adopted specifications such as VESC Regulation V5, or SAE Recommended Practice J697 MAY88, which would apply to vehicles operated within their borders. However, we are unable to advise you on State laws, and suggest that you contact, for an opinion, the American Association of Motor Vehicle Administrators (AAMVA), 4600 Wilson Boulevard, Arlington, Va. 22203. Sincerely, John Womack Acting Chief Counsel; |
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ID: aiam2900OpenMr. Robert J. Shirock, Safety Director, U.S. Army Tank- Automotive Materiel Readiness Command, Department of the Army, Warren, MI 48090; Mr. Robert J. Shirock Safety Director U.S. Army Tank- Automotive Materiel Readiness Command Department of the Army Warren MI 48090; Dear Mr. Shirock: This is in reply to your letter of November 13, 1978, to th Administrator questioning whether certain trucks procured by your Command comply with paragraph S4.5.4 of Federal Motor Vehicle Safety Standard No. 108.; That paragraph states 'The stop lamps on each vehicle shall b activated upon application of the service brakes.' You wrote that 'when the hazard warning lights are activated the stop lamp cannot be activated upon application of the service brakes.' The system you describe would be in compliance with Standard No. 108, if the stop lamps and signal lamps are optically combined, for the following reason. Paragraph S4.4.1 allows combination of a stop lamp with a turn signal lamp (which provides the hazard warning signal). Paragraph 4.2 of SAE Standard J586c *Stop Lamps*, August 1970 (incorporated by reference in Standard No. 108 as the operative standard for stop lamps) requires that 'When a stop signal is optically combined with the turn signal, the circuit shall be such that the stop signal cannot be turned on in the turn signal which is flashing.; This, of course, means that in a combination lamp the stop signa cannot be given while the hazard warning signal is being operated. If the Army deems it desirable it could require a different circuitry in combination lamps by which the stop lamps and hazard warning signal lamps could operate simultaneously, as military vehicles need not conform to Federal safety standards (49 CFR 571.7(c)).; Because several jurisdictions require slow-moving vehicles to use th hazard lamps while in motion, I am asking our Office of Rulemaking to review this prohibition. Thank you for bringing this matter to our attention.; Sincerely, Joseph J. Levin, Jr. Chief Counsel |
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.