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: aiam0175OpenMr. W.J. Sears, Vice President, Rubber Manufacturers Association, 1346 Connecticut Avenue NW., Washington, D.C. 20036; Mr. W.J. Sears Vice President Rubber Manufacturers Association 1346 Connecticut Avenue NW. Washington D.C. 20036; Dear Mr. Sears: This will acknowledge your letter of August 1, 1968, to the Nationa Highway Safety Bureau, requesting the addition of test rims for certain tire size designations to Table II of the Federal Motor Vehicle Safety Standard No. 110.; With your letter you transmitted data indicating satisfactor completion of the test requirements specified in the Federal Motor Vehicle Safety Standards No. 109 and No. 110. On the basis of this information, your request for the approved equivalent rims is granted.; Accordingly, the following approved equivalent rims will be added t Table II of the Federal Motor Vehicle Safety Standard No. 110.; Tire Size Designation Alternate Rim E70-14 7JJ F70-15 8JJ G78-14 7J E70-15 7JJ; Sincerely, H.M. Jacklin, Jr. Acting Director, Motor Vehicle Safet Performance Service; |
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ID: aiam0660OpenMr. Jimmy W. Gerlack, G. and W. Body Works, Post Office Box 585, Durant, OK 74701; Mr. Jimmy W. Gerlack G. and W. Body Works Post Office Box 585 Durant OK 74701; Dear Mr. Gerlack: Thank you for your 'Manufacturer Identification Registration Report with which you submitted a sample of a certification label that you intend to use to fulfill your obligations under Part 567 of Title 49 of the Code of Federal Regulations, soliciting our advice.; The nomenclature on the label fulfills the requirements. However, ther is some question as to whether the material would meet the permanency requirements of section 114 of the National Traffic and Motor Vehicle Safety Act of 1966 (the Act).; The subject is further addressed in the Preamble to the certificatio requirements that became effective on September 1, 1969, '. . . The intent of the requirement is that the label last for the life of the vehicle . . .' (34 F.R. 7031) copy enclosed.; You should assure yourself that the material used will meet thos requirements.; Sincerely, Francis Armstrong, Director, Office of Standard Enforcement, Motor Vehicle Programs; |
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ID: aiam2352OpenMr. Warren M. Heath, Commander, Engineering Section, Department of California Highway Patrol, P.O. Box 898, Sacramento, CA 95804; Mr. Warren M. Heath Commander Engineering Section Department of California Highway Patrol P.O. Box 898 Sacramento CA 95804; Dear Mr. Heath: This is in reply to your letter of June 22, 1976, asking fo interpretations of Motor Vehicle Safety Standards Nos. 108 and 205.; Paragraph S4.3.1 of Standard No. 108 requires, as you noted, that lamp and reflective devices be securely mounted on a rigid part of the vehicle. You asked 'whether or not flexible mount clearance and sidemarker lamps should be permitted for use on motor vehicles.' Your question appears directed towards replacement equipment. The answer is that California may regulate mounts for replacement lighting equipment in the manner it deems appropriate. S4.3.1 applies to the mounting of lighting equipment on new motor vehicles, and does not establish a specification for replacement equipment mounts. The replacement clearance and sidemarker lamps themselves are, of course, subject to Standard No. 108.; You also asked whether there was a provision in Standard No. 205 *Glazing Materials*, that would exempt 'Item 3' [AS 3] glazing (to be used for glass partitions and rear side windows of van-type vehicles) from the requirements of ANS Z26 Tests Nos. 1 and 18.; The answer to your question is no. Paragraph S5.1.1 of Standard No. 20 specifies that glazing materials for use in motor vehicles shall conform to the requirements of ANS Z26. The ANS Z26 specifications require 'Item 3' glazing materials to comply with Test No. 1, 'Light Stability,' and Test No. 18, 'Abrasion Resistance,' regardless of where the 'Item 3' glazing is to be used in the vehicle. Thus, there is no provision by which manufacturers of such glazing may be exempted from the test requirements.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam1610OpenMr. C. E. Bryant, Bendix Home Systems, Inc., 2695 Peachtree Square, Peachtree Industrial Blvd., Doraville, GA 30340; Mr. C. E. Bryant Bendix Home Systems Inc. 2695 Peachtree Square Peachtree Industrial Blvd. Doraville GA 30340; Dear Mr. Bryant: This is in reply to your letter of August 21, 1974, asking whether th terms 'loaded vehicle weight' or 'rated cargo load' include the liquid for both water potable tanks and waste holding tanks in the case of motor homes and multi-purpose passenger vehicles. You indicated in a phone conversation with Mike Peskoe of this office on September 4, 1974, that the purpose of your question is to determine whether the weight of this liquid would be included in a manufacturer's computation of gross vehicle weight rating. You also ask for definitions of 'loaded vehicle weight' and 'rated cargo load.'; It is not required that a determination of gross vehicle weight ratin include the weight of a full amount of liquid in both the potable and the waste holding tanks on the assumption, stated in your letter, that in actual use the holding tank is empty when the potable tank is filled, and the liquid is drawn gradually from one tank to the other. It should be placed in the potable tank for determining GVWR, for this more closely reflects a new vehicle configuration.; The term 'loaded vehicle weight' is not defined in the Federal moto vehicle safety standards or regulations nor are we aware of its use therein. A related term, 'maximum loaded vehicle weight,' is defined in Motor Vehicle Safety Standard No. 110 (49 CFR 571.110), but this definition is not applicable to your question. 'Rated cargo load' is also not specifically defined, but is used in the requirements for gross vehicle weight rating in 49 CFR 567 and as a test condition in Motor Vehicle Safety Standard No. 208. It is intended to mean the manufacturer's good faith rating of the weight of a vehicle's full cargo.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam1499OpenMr. E.J. Wagner, Manager, Director, American Retreaders' Assoc., Inc., P.O. Box 17203, Louisville, Kentucky 40217; Mr. E.J. Wagner Manager Director American Retreaders' Assoc. Inc. P.O. Box 17203 Louisville Kentucky 40217; Dear Mr. Wagner: This is in reply to your letters of April 7 and April 8, 1974 regarding Standard No. 117, 'Retreaded Pneumatic Tires.' Your April 7 letter asks whether Standard No. 117 requires treadwear indicators to be straight across the tread face. Your letter of April 8 encloses two sample rubber labels and asks whether each conforms to the requirements of S6.3 of Standard No. 117.; Paragraph S5.1.1(b) of Standard No. 117 does not specify configuration for treadwear indicators. Rather, it incorporates by reference the requirements for treadwear indicators of S4.2.1(d) of Standard No. 109, which calls only for a treadwear indicator that provides a 'visual indication that the tire has worn to a tread depth of 1/16 inch.' We do not construe this language to require a straight-across treadwear indicator and other configurations are therefore permitted.; With respect to the labeled you enclose in your letter of April 8, eac would conform to all of the requirements of S6.3 (which includes the requirements for both affixed (S6.3.1) and permanent (S6.3.2) labeling) if the tires to which they are affixed are of neither bias-belted or radial construction. If they are of either of these construction types, that information would have to be retention of the original casing labeling.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam2511OpenMr. Dave Murray, Harley Murray, Inc., 1754 E. Mariposa Road (So. Highway 99), Stockton, CA 95206; Mr. Dave Murray Harley Murray Inc. 1754 E. Mariposa Road (So. Highway 99) Stockton CA 95206; Dear Mr. Murray: This responds to your January 25, 1977, question whether a row of eigh wheels arranged in a line that is perpendicular to the longitudinal axis of a vehicle constitute an 'axle' as that word is used in S3(b) of Standard No. 121, *Air Brake Systems*. You note that the wheels are not mounted on a single solid axle but rather are mounted on two walking beam assemblies that also constitute the suspension for a separate set of eight wheels across the vehicle.; The answer to your question is yes. When asked for a definition o 'axle system' in connection with Standard No. 121, the National Highway Traffic Safety Administration stated:; >>>In answer to Wagner's request for a definition of 'axle system,' th term is used in the same sense as it is used in the definition of GAWR found at 49 CFR 571.3. 'Axle system' is used instead of 'axle' to avoid confusion in situations where a suspension system does not employ an axle. The term has not created difficulty in the GAWR definition (39 FR 17553, May 17, 1974).<<<; The agency's use of 'axle' in S3 is intended to be identical to its us of the phrase 'axle system.' Thus, 'axle' means the arrangement of wheels that lie across the vehicle in a line that is perpendicular to the longitudinal centerline of the vehicle. This understanding of 'axle' and 'axle system' is used regularly in the assignment of gross axle weight ratings (GAWR) on vehicles that employ independent suspensions in place of solid axles.; From your description, it appears that each row of eight wheels on you trailer constitutes an 'axle' or 'axle system' that could be rated at a GAWR in excess of 29,000 pounds, qualifying the vehicle for exclusion from Standard No. 121.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam1243OpenMr. David E. Martin, Manager, Automotive Safety Engineering, Environmental Activities Staff, General Motors Technical Center, General Motors Corporation, Warren, MI 48090; Mr. David E. Martin Manager Automotive Safety Engineering Environmental Activities Staff General Motors Technical Center General Motors Corporation Warren MI 48090; Dear Mr. Martin: Dr. Gregory has asked me to reply to your letter of August 28, 1973, i which you request our endorsement of new labels General Motors intends to use to fulfill its responsibilities under part 567 of Title 49 of the Code of Federal Regulations.; The wording on the label meets the requirements of paragraph 567.4(g) The color of the paint under the label 'window' would determine conformity with the contrasting color requirements in paragraph 567.4(f).; It would appear that the material would '. . . be permanently affixed . .' if it '. . . is tightly bonded to the surface of the vehicle panel. . . .' However, it has not been the practice of the National Highway Traffic Safety Administration to endorse label materials.; Thank you for your continuing cooperation. Sincerely, Robert L. Carter |
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ID: aiam1242OpenMr. David E. Martin, Manager, Automotive Safety Engineering, Environmental Activities Staff, General Motors Technical Center, General Motors Corporation, Warren, MI 48090; Mr. David E. Martin Manager Automotive Safety Engineering Environmental Activities Staff General Motors Technical Center General Motors Corporation Warren MI 48090; Dear Mr. Martin: Dr. Gregory has asked me to reply to your letter of August 28, 1973, i which you request our endorsement of new labels General Motors intends to use to fulfill its responsibilities under part 567 of Title 49 of the Code of Federal Regulations.; The wording on the label meets the requirements of paragraph 567.4(g) The color of the paint under the label 'window' would determine conformity with the contrasting color requirements in paragraph 567.4(f).; It would appear that the material would '. . . be permanently affixed . .' if it '. . . is tightly bonded to the surface of the vehicle panel. . . .' However, it has not been the practice of the National Highway Traffic Safety Administration to endorse label materials.; Thank you for your continuing cooperation. Sincerely, Robert L. Carter |
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ID: aiam1241OpenMr. David E. Martin, Manager, Automotive Safety Engineering, Environmental Activities Staff, General Motors Technical Center, General Motors Corporation, Warren, MI 48090; Mr. David E. Martin Manager Automotive Safety Engineering Environmental Activities Staff General Motors Technical Center General Motors Corporation Warren MI 48090; Dear Mr. Martin: Dr. Gregory has asked me to reply to your letter of August 28, 1973, i which you request our endorsement of new labels General Motors intends to use to fulfill its responsibilities under part 567 of Title 49 of the Code of Federal Regulations.; The wording on the label meets the requirements of paragraph 567.4(g) The color of the paint under the label 'window' would determine conformity with the contrasting color requirements in paragraph 567.4(f).; It would appear that the material would '. . .be permanently affixed. .' if it '. . .is tightly bonded to the surface of the vehicle panel. . . .' However, it has not been the practice of the National Highway Traffic Safety Administration to endorse label materials.; Thank you for your continuing cooperation. Sincerely, Robert L. Carter |
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ID: aiam3367OpenMr. G. Montgomery Spindler, Uniroyal, Inc., 1700 K Street, N.W., Washington, DC 20006; Mr. G. Montgomery Spindler Uniroyal Inc. 1700 K Street N.W. Washington DC 20006; Dear Mr. Spindler: This is in response to your letter of October 10, 1980, requestin clarification of the explanation of Treadwear grading in Figure 2 of the Uniform Tire Quality Grading (UTQG) Standards (49 CFR S 575.104). You ask whether the explanation can be interpreted to mean that the relative treadwear performance of different tires on the UTQG test course in San Angelo, Texas will be consistent with the relative performance of the tires when driven under comparable conditions on other roads.; In experimental testing leading to promulgation of the UTQG regulation the National Highway Traffic Safety Administration (NHTSA) tested the treadwear of various tire lines not only on the San Angelo course but on roads in other parts of the country. The agency concluded that the UTQG grades established for different tires in testing on the San Angelo course accurately represent the relative performance of the tires obtainable on roads elsewhere in the United States, assuming that the tires to be compared are run under identical conditions.; The statement in Figure 2 of the UTQG regulation that a tire graded 15 would wear one and one-half times as well on the government course as a tire graded 100 was not intended to suggest that the tire would not wear one and one-half times as well on another course, if conditions of use were controlled. The term 'relative performance' in Figure 2 refers to the performance of tires in comparison to other tires, and the term 'norm' refers to the consistently obtainable relative performance of tires when tested under controlled conditions. Thus, the explanation indicates that, although the relative performance of different tires will be consistent when the tires are tested under controlled conditions, this relative performance may not be obtainable in actual use, if one tire is subjected to more severe road or weather conditions, abusive driving or improper maintenance.; NHTSA will provide confidential treatment for your October 10, 1980 letter.; Sincerely, Frank Berndt, 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.