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 |
|---|---|
| search results table | |
ID: aiam5488OpenMr. 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"; |
|
ID: aiam1977OpenMr. H. Ray Cozad, FMC Corporation, Crane & Excavator Division, 1201 Sixth Street Southwest, Cedar Rapids, IA 52406; Mr. H. Ray Cozad FMC Corporation Crane & Excavator Division 1201 Sixth Street Southwest Cedar Rapids IA 52406; Dear Mr. Cozad: This responds to FMC Corporations' June 23, 1975, request fo clarification of a recent NHTSA proposal (40 FR 24915, June 11, 1975) to amend Standard No. 121, *Air brake systems*, to establish an exemption criterion for a vehicle that has an 'unloaded vehicle weight that is not less than 95 percent of the vehicle GVWR gross vehicle weight rating '. You ask whether a vehicle's 'unloaded weight' means the GVWR, as established by adding the gross axle weight ratings (GAWR) of all axles, minus whatever portions of the vehicle are removed for highway travel.; The answer to your question is no. In light of the requirements fo GVWR in Part 567.4 (Certification), unloaded vehicle weight will normally be the GVWR of the vehicle minus its rated cargo load and its assigned occupant weight (at least 150 lbs). The rated cargo load would not include the weight of portions of a vehicle which are essential to its specialized function but are removed in accordance with State regulation for transit purposes.; I would also note that the NHTSA definition of GVWR (49 CFR S 571.3 does not require that the GVWR be the sum of the vehicle's GAWR's. Of course the GVWR must not exceed the sum of vehicle GAWR's.; With regard to your June 17, 1975, suggestion of a meeting with Mr Larson, I would prefer first to have your view of these clarifications.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
|
ID: aiam0665OpenMr. R. E. Kennel, Manager, Technical Services, The Budd Company, Automotive Division, Detroit, MI 48215; Mr. R. E. Kennel Manager Technical Services The Budd Company Automotive Division Detroit MI 48215; Dear Mr. Kennel: This is in reply to your letter of March 10, 1972, in which yo presented a series of questions concerning the meaning of several requirements of Federal Motor Vehicle Safety Standard No. 121, 'Air Brake Systems.' Our reply deals with the questions in the order you asked them.; >>>1. Your first question concerns the meaning of the statement i section S5.4 that 'a brake assembly that has undergone a road test pursuant to S5.3 need not conform to the requirements of this section.' To parahprase (sic) your question, the quoted language means that if a given brake assembly is subjected to the road test, the same brake assembly with the used lining need not conform to the dynamometer requirements. Conformity to the dynamometer requirements will be determined by testing an identical brake assembly with new linings. The petitions for deletion of dynamometer testing would have made the road test the only test. The standard requires both tests, even though two sets of identical brakes will be used, and our statement that the petitions were denied is therefore correct.; 2. You point out that the measurement interval used in S5.4.1.1 fo determining average torque, which begins when a specified pressure is reached, differs from the interval specified in S5.4 for measuring deceleration, which begins with the onset of deceleration. Although we agree that you may need different instrumentation for measuring average torque and average deceleration, we do not agree that their is any conflict since average torque and average deceleration are not required to be measured at the same time. We consider the present method of measuring torque and deceleration to be the correct methods.; 3. The typographical error in section S5.4.1.1, which you hav correctly edited to read 'Repeat the procedure six times, increasing the brake chamber air pressure by 10 psi each time,' has been corrected by a revision in the March 29, 1972, *Federal Register*.; 4, 5, 6. The requirements of S5.4.2, S5.4.2.1 and S5.4.3 concernin average deceleration rates should not be understood to mean that a manufacturer, in his own testing, must test at exactly that rate. It is advisable for him to test in a manner that offers assurance that the brakes will pass when tested in the manner specified in the standard. Typically, where a test value such as 9 fpsps is specified, manufacturers tend to use more adverse values in their own testing. Under the former wording of these sections, the compliance agency could have tested brakes at decelerations higher than the specified minimum, and it would have been much more difficult for a manufacturer to ascertain his 'worst case' situation.<<<; The notice ofoposing (sic) to amend the weight conditions fo truck-tractors should be issued within the next two months.; Sincerely, E. T. Driver, Director, Office of Operating Systems, Moto Vehicle Programs; |
|
ID: aiam2658OpenMr. Bernhard Schwartz, Sales Manager, Sate-Lite Mfg. Co., 4600 North Olcott Avenue, Harwood Heights, Illinois 60656; Mr. Bernhard Schwartz Sales Manager Sate-Lite Mfg. Co. 4600 North Olcott Avenue Harwood Heights Illinois 60656; Dear Mr. Schwartz: This responds to your August 2, 1977, letter asking whether you ca submit to the National Highway Traffic Safety Administration (NHTSA) a piece of your equipment for confirmation that it complies with Standard No. 125, *Warning Devices*.; The NHTSA does not issue advance approvals of equipment or moto vehicles manufactured in accordance with the safety standards. It is the responsibility of each manufacturer of motor vehicles or equipment to ensure that his motor vehicle or equipment complies with the requirements. Therefore, it is not necessary for you to submit your design to the NHTSA prior to its production.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
|
ID: aiam5467OpenMr. Michael Love Manager, Compliance Porsche Cars North America, Inc. P.O. Box 30911 Reno, Nevada 89520-3911; Mr. Michael Love Manager Compliance Porsche Cars North America Inc. P.O. Box 30911 Reno Nevada 89520-3911; Dear Mr. Love: We have received your letter of November 29, 1994 asking for an interpretation of 49 CFR Part 591. Specifically, Porsche wishes to import vehicles for the Canadian market through the Port of Charleston, where certain processing activities will be performed on the cars before they are exported to Canada. The temporary importation of Canadian-market cars would be through 591.5(c) which allows importation 'solely for export', provided that the vehicle is so labeled. You have asked for our concurrence in your interpretation of 591.5(c). We agree that Porsche may import and export Canadian-market cars under this section of the importation regulation. You foresee a situation in which 'a Canadian vehicle with a unique combination of options might be sought by a U.S. customer'. Porsche would like to be able to convert the vehicle to comply with the U.S. Federal motor vehicle safety standards after importation and before it leaves Porsche's control. Porsche would also like to be able to re-import from Canada into the U.S. vehicles that would be converted to U.S. specifications. You have asked for confirmation that these operations would also be permissible under 591.5(c). Importation of noncomplying motor vehicles into the United States and their subsequent conversion to the U.S. Federal motor vehicle safety standards must be accomplished through the mechanisms established by Congress in the Imported Vehicle Safety Compliance Act of 1988 (now 49 U.S.C. 30141 et seq.). First, NHTSA must have decided that the vehicle is eligible for importation pursuant to 49 CFR Part 593. Second, a vehicle intended for sale must be imported under bond by one who has been designated a Registered Importer under 49 CFR Part 592, who will undertake to bring the vehicle into compliance and to submit appropriate proof of this to NHTSA. Porsche may become a Registered Importer by filing an application under Part 592. If a vehicle intended for the Canadian market has been temporarily imported under 591.5(c), and Porsche then wishes to convert it to U.S. specifications rather than export it to Canada, you should telephone Clive Van Orden, Office of Vehicle Safety Compliance (202-366-2830), to apprise him of the situation. We see no problem in this as long as NHTSA has decided that the vehicle is eligible for importation and Porsche provides a compliance package, in accordance with the requirements of Parts 592 and 593. Sincerely, Philip R. Recht Chief Counsel; |
|
ID: aiam0235OpenMr. Kenneth L. Rosenberger, 22112 A Sherman Avenue, Riverside, California 92508; Mr. Kenneth L. Rosenberger 22112 A Sherman Avenue Riverside California 92508; Dear Mr. Rosenberger: This is in reply to your letter of April 18, 1970, concerning the us of tires designed for racing purposes for street use.; The National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1381 *e seq.*) prohibits the sale of motor vehicle equipment that does not comply with applicable Federal Motor Vehicle Safety Standards. therefore, it would be a violation of the Act if someone manufactured or sold a passenger tire that did not meet Standard No. 109. However, the Act does not apply the use of non-conforming tires so that it would be the sale of such tires for street purposes, not the use, that would be a violation of the Act.; With regard to your comments that the California Highway Patro considers these tires 'OK' for street use, we understand that the restriction in the California regulations is presently limited to the prohibition of the sale of racing tires for street use but that legislation has been introduced which would prohibit the use of such tires for street purposes.; Sincerely, Rodolfo A. Diaz, Acting Associate Director, Motor Vehicl Programs; |
|
ID: aiam2208OpenMr. J. Trimble, Secretary General, European Tyre and Rim Technical Organisation, Avenue Brugmann, 32 Bte 2, 1060 Bruxelles, Belgium; Mr. J. Trimble Secretary General European Tyre and Rim Technical Organisation Avenue Brugmann 32 Bte 2 1060 Bruxelles Belgium; Dear Mr. Trimble: This is in response to your letter of January 26, 1976, which inquire about the status of the E.T.R.T.O. petition for an amendment of Federal Motor Vehicle Safety Standard No. 119, *New Pneumatic Tires for Vehicles Other Than Passenger Cars*, concerning tires for low-power motorcycles with restricted speed capability.; We expect to issue a Federal Register notice on this subject in th near future.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
|
ID: aiam5037OpenMr. M. K. Chaudhari Director ARAI The Automotive Research Association of India Survey No. 102 Vetal Hill Off Paud Road, Kothrud Pune-411 004 India; Mr. M. K. Chaudhari Director ARAI The Automotive Research Association of India Survey No. 102 Vetal Hill Off Paud Road Kothrud Pune-411 004 India; "Dear Mr. Chaudhari: This responds to your letter requesting th testing procedure for and test results of vehicles equipped with anti-skid brake systems. These systems are also referred to as anti-lock brake systems. You also requested the addresses of equipment manufacturers that produce anti-lock brake systems. I am pleased to have this opportunity to provide you information about this topic. By way of background information, the National Highway Traffic Safety Administration (NHTSA) does not provide approvals of motor vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act ('Safety Act'), it is the responsibility of the manufacturer to ensure that its vehicles or equipment comply with applicable standards issued by this agency. A manufacturer then certifies that its vehicles or equipment comply with the applicable standards. I am enclosing a copy of an information sheet entitled, 'Information for New Manufacturers of Motor Vehicles and Motor Vehicle Equipment,' which explains a manufacturer's responsibility under NHTSA's regulation. I am also enclosing a copy of the two safety standards issued by NHTSA that apply to brake systems: Standard No. 105, Hydraulic Brake Systems (49 CFR 571.105) and Standard No. 121, Air Brake Systems (49 CFR 571.121). These standards are intended to insure the safe braking performance of vehicles under normal and emergency conditions. Vehicle manufacturers are required to certify that vehicles they manufacture comply with these performance-oriented standards. Nothing in these standards currently specifies that vehicles be equipped with an anti-lock device. For your information, the agency is considering proposing additional requirements that might require medium and heavy duty vehicles to be equipped with anti-lock brake systems. A copy of that notice is enclosed (57 FR 24212, June 8, 1992). In addition, the agency has issued a supplemental notice of proposed rulemaking in which the agency is considering whether to harmonize its passenger car brake standard with international standards. (56 FR 30528, July 3, 1991). A copy of that notice is also enclosed. With respect to your request for test results related to anti-lock brake performance, I am enclosing the agency's most recent report on this topic. It is entitled 'Improved Brake Systems for Commercial Motor Vehicles.' With respect to your inquiry requesting the addresses of equipment manufacturers, the agency is unable to provide such information. The following associations may be able to help you obtain this information: Motor Vehicle Manufacturers Association 7430 Second Avenue, Suite 300, Detroit, MI 48202 (Telephone No. 313-872-4311, Fax No. 313-872-5400) Brake System Parts Manufacturers Council 300 Sylvan Avenue P.O. Box 1638 Englewood Cliffs, N.J. 07632-0638 (Tel. No. 201-569-8500, Fax No. 569-0159) I hope this information is helpful. If you have any further questions about NHTSA's safety standards, please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992. The fax number is (202) 366-3820. Sincerely, Paul Jackson Rice Chief Counsel Enclosures"; |
|
ID: aiam3049OpenMr. Herman L. Massie, Chief of Pupil Transportation, Department of Education, Columbus, OH 43215; Mr. Herman L. Massie Chief of Pupil Transportation Department of Education Columbus OH 43215; Dear Mr. Massie: This responds to your June 15, 1979, letter asking about the use o standard production vans for the transportation of school children to or from school or related events. In particular, you ask whether a 15-passenger Dodge Maxi-Van can be used for school transportation.; Whether a new vehicle sold for use as a school vehicle must comply wit the Federal school bus safety standards depends on whether the vehicle meets our definition of a bus. Our definition provides that a bus is 'a motor vehicle with motive power, except a trailer, designed for carrying more than 10 persons.' (Title 49 of the Code of Federal Regulations, Part 571.3). Thus, a vehicle that transport (sic) 10 or fewer persons may be sold as a school vehicle and need not comply with the Federal school bus safety standards. However, a Dodge Maxi-Van capable of carrying 15 persons is a bus. If such a vehicle is sold new for use as a school vehicle, it must comply with those standards.; Sincerely, Frank Berndt, Chief Counsel |
|
ID: aiam1074OpenMr. Stan Haransky, Associate Director, School Bus Manufacturers Institute, 5530 Wisconsin Avenue, Suite 1220, Washington, DC 20015; Mr. Stan Haransky Associate Director School Bus Manufacturers Institute 5530 Wisconsin Avenue Suite 1220 Washington DC 20015; Dear Mr. Haransky: This is in response to the two petitions for rulemaking dated Februar 15, 1973, that you submitted with respect to safety standards applicable to school buses. In one you requested that future standards applicable to school buses become effective on January 1, rather than September 1 as is customary with respect to passenger car standards. Your second petition made a specific request that the effective date of the Bus Window Retention and Release Standard, No. 217, which is set at September 1, 1973, be delayed until January 1,1974. The reason you gave was that the normal model changeover period of the school bus industry is around the first of the year, while September 1 is in the middle of the peak production season.; Your first petition did not mention any specific standards, and i really a general request that the NHTSA take into account the normal model changeover period of the school bus industry in making effective date decisions. This request appears to be reasonable, and we will certainly consider that factor with respect to standards that are as yet unissued.; The situation is different, however, in the case of Standard No. 217 The standard was published on May 10, 1972, more than fifteen months before its effective date. We consider this standard to be a very important one from a safety standpoint. Furthermore, the public concern over the safety of school buses is at an extremely high level. It appears probable that school bus buyers, who have become very safety conscious, have been relying on this effective date in their purchasing decisions.; We have been given no evidence that this standard will requir extensive redesign and retooling, and even if it did, a four-month delay imposed only a few months before the scheduled effective date would hardly be ameliorative. We have no reason to disbelieve your statements concerning the normal changeover period of the industry, but surely at this late date the industry must have taken the imminent effective date of Standard 217 into consideration in its production planning.; In consideration of all these factors, we do not judge it to be in th public interest to grant a delay in the effective date of Standard 217 on the basis of the reason you have provided, namely, the normal production cycle of the industry. If you wish to provide more detailed information concerning technological or economic difficulties that may be caused by the effective date of this standard, we will be willing to consider it.; Sincerely, James E. Wilson, Acting Administrator |
|
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.