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: aiam1298OpenMr. H. Braun, Engineering Supervisor-Production, Motor Coach Industries, Inc., Pembina, ND; Mr. H. Braun Engineering Supervisor-Production Motor Coach Industries Inc. Pembina ND; Dear Mr. Braun: This is in reply to your letter of September 5, 1973, to Mr. Schneide asking whether you may furnsih (sic) side turn signal lamp for inter-city buses at the rear wheels, and if so, the required color.; It is correct that there are no Federal safety requirements for sid turn signal lamps. Therefore, there is no Federal prohibition against your providing such a lamp, and such restrictions as may exist would be those imposed by the States.; Rear mounted turn signal lamps under Federal Standard No. 108 may b either red or amber.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam4560OpenMr. Jack McCroskey Ms. Glenda Swanson Lyle Regional Transportation District 1600 Blake Street Denver, CO 80202-1399; Mr. Jack McCroskey Ms. Glenda Swanson Lyle Regional Transportation District 1600 Blake Street Denver CO 80202-1399; "Dear Mr. McCroskey and Ms. Lyle: This responds to your letter o September 13, 1988, asking for our advice on potential safety hazards and legal liabilities that might result from ignoring the speed restrictions on the tires used on your transit buses. You stated that your entity operates three types of bus service in the State of Colorado. The first type is a local bus, operated primarily in areas where the speed limit is 35 miles per hour (mph), the second type is an express bus, operated primarily in areas where the speed limit is 55 mph, and the third type is a regional bus, operated primarily on freeways with speed limits of 55 to 65 mph. You were interested primarily in the tires used on your express buses. You stated that you use two types of speed-restricted tires 'almost interchangeably' on the express buses. One of your speed-restricted tire types is the XT, which is speed-restricted to a maximum speed of 55 mph. The other is the DXT, which is speed-restricted to a maximum speed of 35 mph. Since the express buses are operated primarily at speeds of 55 mph, you contacted the tire manufacturer to get its advice on the acceptability of using tires that are speed-restricted to 35 mph on these buses. You enclosed copies of correspondence you received from the manufacturer, stating that its DXT and XT tires are identical, except that the DXT tire has 7/32 of an inch more undertread. The manufacturer's advice was that the tire that is speed-restricted to a maximum of 35 mph 'may be used at higher speeds, but not for sustained operation.' You asked whether it is advisable for your entity to continue using the tires that are speed-restricted to 35 mph on your express buses, which operate primarily at 55 mph. We strongly recommend that you not do so. There are some notable advantages associated with speed-restricted tires, including enhanced load-carrying capabilities and greater resistance to tire damage from hitting objects in the road or curbs. However, the greater undertread on speed-restricted tires also means that the tires will generate higher temperatures at high speeds than a comparable non-restricted tire. Higher temperatures inside the tire increase the chances of a tire failure at high speeds. NHTSA carefully considered both the advantages of speed-restricted tires and the need to ensure that such tires are properly used when it was developing Standard No. 119, New Pneumatic Tires for Motor Vehicles Other Than Passenger Cars (49 CFR 571.119, copy enclosed). Every new bus tire must be certified by its manufacturer as complying with this standard. This agency decided that Standard No. 119 should permit the continued production of speed-restricted tires, but with appropriate safeguards to ensure that these tires would not be used at higher speeds. Accordingly, Standard No. 119 specifies less stringent high speed and endurance test requirements for speed-restricted tires. Speed-restricted tires for use on vehicles other than motorcycles are exempted from the high speed performance requirements of S6.3 of Standard No. 119. This exemption reflects the fact that the tires are not designed for high speed use. For the same reason, the endurance test schedule for speed-restricted tires consists of a lower test speed and fewer total revolutions of the test wheel, as shown in Table III of Standard No. 119. Hence, the manufacturer of these speed-restricted tires has not certified that these tires comply with the performance requirements of Standard No. 119 under conditions exceeding the speed-restriction marked on the tires. To ensure that the user of speed-restricted tires would not operate the tires at higher speeds than those at which the tires are designed to operate safely, section S6.5(e) of Standard No. 119 requires every speed-restricted tire to have the marking 'Max speed mph' on the sidewall. This marking is intended to alert the tire user of the limitations of this tire, so that it will not be repeatedly used at higher speeds. Since your express buses operate primarily at speeds of 55 mph, we urge you not to equip those buses with tires labeled 'Max speed 35 mph.' Similarly, since your express and regional buses typically operate at speeds exceeding 55 mph on their routes, we recommend only tires without speed restrictions for these buses. With respect to your question about potential legal liabilities in the event one of these speed-restricted tires fails while in service on one of your express buses, that is a question of State law. Since I am not familiar with the Colorado law on this subject, I must decline to offer an opinion. However, the Attorney General for the State of Colorado or other local counsel would be able to accurately advise you on Colorado's law in this area. Sincerely, Erika Z. Jones Chief Counsel Enclosure"; |
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ID: aiam1762OpenMr. Donald J. Gobeille,Volvo of America Corporation,Rockleigh, New Jersey 07647; Mr. Donald J. Gobeille Volvo of America Corporation Rockleigh New Jersey 07647; Dear Mr. Gobeille::#Please forgive the delay in responding to you letter of November 19, 1974, which requested an interpretation of the labeling requirements of Federal Motor Vehicle Safety Standard No. 106-74, *brake Hoses*, as applied to short lengths of vacuum brake hose.#To fit the information required by S9.1 of the standard on short lengths of hose, you have suggested a labeling format consisting of the required information presented in two lines,#>>>'each in block capital letters and numerals at least one eighth inch high, placed adjacent to one another and separated by the minimum space necessary to assure clarity. The label would occupy no more than three eighths of an inch on a hose approximately two inches in circumference (5/8 inch OD)'.<<<#Because the two lines would be close enough to prevent confusion with any optional labeling which might appear on the opposite side of the hose, it appears that the format you have described complies with the requirements of S9.1 of Standard No. 106-74. #Yours truly,Richard B. Dyson,Acting Chief Counsel; |
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ID: aiam0870OpenMr. Keith Morton, Para-Chem Southern, Inc., P.O. Box 127, Simpsonville, SC, 29681; Mr. Keith Morton Para-Chem Southern Inc. P.O. Box 127 Simpsonville SC 29681; Dear Mr. Morton: This is in reply to your letter of September 28, 1972, concerning th application of Paragraph S5.2.2 of Motor Vehicle Safety Standard No. 302, 'Flammability of Interior Materials.' You ask whether, in testing automotive interior fabrics, test specimens 'must be burned in warp and filling directions only, or does it also include testing in the face-down (inverted) positions?' As you point out, under the standard test specimens for each component are to be tested 'so as to provide the most adverse results.' This means that the relevant test result is the most adverse one achieved in any horizontal orientation, either upward- or downward-facing. How you determine which positioning of the test specimen produces the most adverse results is within your own discretion.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1277OpenMr. Donald Gary Hayes, Robertson Tank Lines Inc., P.O. Box 1505, Houston, Texas 77001; Mr. Donald Gary Hayes Robertson Tank Lines Inc. P.O. Box 1505 Houston Texas 77001; Dear Mr. Hayes: This is in reply to your letter of August 30, 1973, requesting a DO code number for retreaded tires you manufacture. It appears from your letter that the tires you retread are truck tires intended solely for your company's own use.; Any tires retreaded by and solely for use by Robertson Tank Lines ar exempt from NHTSA recordkeeping requirements and a code number is not required. As truck retreads are not subject to and Federal motor vehicle safety standard, you are also not required to place a 'DOT' symbol on them. If you retread passenger car tires, however, you are required to place a 'DOT' symbol on the tire sidewall (indicating conformity to Federal Motor Vehicle Safety Standard No. 117).; Yours truly, Richard B, Dyson, Assistant Chief Counsel |
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ID: aiam2722OpenMr. Philip H. Taft, Director, Tire Retreading Institute, National Tire Dealers & Retreaders Association, Inc., 1343 L Street, N.W., Washington, D.C. 20005; Mr. Philip H. Taft Director Tire Retreading Institute National Tire Dealers & Retreaders Association Inc. 1343 L Street N.W. Washington D.C. 20005; Dear Mr. Taft: This responds to your October 27, 1977, letter asking whether a tir retreader is permitted to change the designation of a tire from 'tubeless' to 'tubetype'.; Standard No. 117, *Retreaded Pneumatic Tires*, requires that th information appearing on the tire sidewall be the same as that which appeared on the tire as originally manufactured. This is indicated by the language in paragraph S6.3. If a retreader changed the tire designation from 'tubeless' to 'tubetype', he would be altering the information that was associated with the original tire. Thus, a retreader is not permitted to change the tire designation in the manner you describe.; Sincerely, Joseph J. Levin Jr., Chief Counsel |
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ID: aiam2372OpenMr. Don Dekker, Attwood Corporation, Lowell, MI, 49331; Mr. Don Dekker Attwood Corporation Lowell MI 49331; Dear Mr. Dekker: This is in response to your letter of June 23, 1976, in which you as whether Standard No. 302, *Flammability of Interior Materials*, applies to portable toilets.; Standard 302 applies to the motor vehicles listed in Section S3 including the equipment installed in them at the time of sale. Section S4 lists those parts of a motor vehicle that must comply with burn resistance requirements, and a portable toilet is not included. Therefore, it is not subject to the standard. I have enclosed a copy of the standard for your information.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam2688OpenMr. Dudley E. DeWitt, Assistant Director of Engineering, Great Dane Trailers, Inc., Lathrop Avenue, P.O. Box 67, Savannah, GA 31402; Mr. Dudley E. DeWitt Assistant Director of Engineering Great Dane Trailers Inc. Lathrop Avenue P.O. Box 67 Savannah GA 31402; Dear Mr. DeWitt: This responds to your July 8, 1977, letter posing several hypothetica questions concerning the responsibility to attach a new label to a vehicle if altered prior to first purchase for purposes other than resale.; Section 108(b)(1) of the National Traffic and Motor Vehicle Safety Act 15 U.S.C. 1397(b)(1), states that the prohibition against the delivery of a nonconforming vehicle 'shall not apply to the introduction or delivery for introduction in interstate commerce of any motor vehicle.....after the first purchase of it in good faith for purposes other than resale.' You ask at what point in time the 'first purchase' is deemed to have occurred. We have taken the position that the purchase is not complete until the vehicle is delivered to the purchaser.; In general, the issuance of title to which you refer in your letter i irrelevant to a determination of whether there is a need for the manufacturer's representative to attach a new label to an altered vehicle, as required by Part 567.7, *Certification*. Delivery of the vehicle is the point at which the first purchase is complete and the responsibility to attach a new label ceases. We would note that if the issue of vehicle modification is raised and decided upon during the sales conversations we would consider a subsequent modification occurring after the point of delivery to be an event requiring the attachment of a new label.; In particular response to your hypotheticals, paragraphs B and through H represent occasions when vehicle alterations would result in the need to attach a new label in accordance with the requirements of Part 567.7. The reason for this conclusion is that all of the hypotheticals result in the alteration of the gross vehicle weight rating (GVWR), or gross axle weight ratings (GAWR) or the attachment or removal of non-readily attachable components. There would be no need, in paragraphs B and D, to attach a new label if the vehicle manufacturer had availed himself of the option of listing alternative GAWR's, with appropriate tire sizes, as long as the newly installed tires were among those listed on the certification label.; Paragraphs A and C do not represent alteration situations in which th GVWR or the GAWR are affected. Although the tires would have a greater load capacity than that rated on the vehicle label, there is no need to change the rating of the vehicle, as is the case when tires are installed that have lower load capacities. Further, the installation of tires constitutes the installation of readily attachable components. Therefore, there is no need to attach a new label in accordance with Part 567.7 in these situations.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam5458OpenMr. Clay F. West Garvey, Schubert & Barer Eighteenth Floor Second & Seneca Building 1191 Second Avenue Seattle, WA 98101-2939; Mr. Clay F. West Garvey Schubert & Barer Eighteenth Floor Second & Seneca Building 1191 Second Avenue Seattle WA 98101-2939; Dear Mr. West: This responds to your letter of November 1, 1994 requesting information on any rules or standards applicable to a 'windshield cleaning device.' As your letter describes, '(t)he product is a clear strip which is adhered to the windshield of an automobile. The action of the wiper blades passing over the device causes the wiper blades to function more effectively.' I am enclosing a copy of a May 29, 1992 letter to Mr. John J. Jacoby concerning a similar device. I believe this letter contains the information you need. If you have any other questions, please contact Mary Versailles of my staff at this address or by phone at (202) 366-2992. Sincerely, Philip R. Recht Chief Counsel Enclosures; |
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ID: aiam3975OpenMr. K. Weight, 65 E. 200 N., Provo, UT 84601; Mr. K. Weight 65 E. 200 N. Provo UT 84601; Dear Mr. Weight: Thank you for your letter to Secretary Dole concerning black windows i automobiles. Your letter was referred to the National Highway Traffic Safety Administration since we are the agency that issues Federal Motor Vehicle Safety Standards (FMVSS). We have issued FMVSS No. 205, *Glazing Materials*, which sets performance requirements, including light transmittance requirements, for glazing used in motor vehicles. As explained below, FMVSS No. 205 limits the use of darkly tinted windows.; FMVSS No. 205 requires glazing, both tinted and untinted, in a ne passenger car to transmit at least 70 percent of the light that falls on it. To give you an idea of what level of tinting is allowed, please consider the following examples. If a window were completely open, the light transmitted through the opening would be 100 percent, clear windows have about 90 percent light transmittance, while factory-equipped tinted windows in new vehicles have about 80 percent light transmittance.; Minimum visibility levels are necessary to allow the average driver t detect other vehicles, pedestrians, bicyclists and traffic and road signs under all lighting conditions. Were the light transmittance *less* than 70 percent, such as found in darkly tinted glazing, visibility would be reduced to the extent that it could pose a safety hazard. From your description, I assume that the light transmittance of the 'black window' is less than 70 percent. A situation where the light transmittance is below 70 percent may be in violation of FMVSS No. 205.; No manufacturer or dealer is permitted to install tinting material i new vehicles without certifying that the vehicle continues to be in compliance with the light transmittance requirements of the standard. If a dealer, manufacturer, repair business or distributor installs dark tinting material in a used vehicle, then a violation of Section 108(a)(2)(A) of the National Traffic and Motor Vehicle Safety Act may result. That section provides that none of these persons may knowingly render inoperative any device or element of design installed on or in a motor vehicle or item of motor vehicle equipment in compliance with an applicable motor vehicle safety standard. Violation of the 'render inoperative' provision can result in Federal civil penalties of up to $1,000 for each violation.; Owners of used vehicles may, themselves, alter their vehicles, so lon as the vehicle adheres to all State requirements. Under Federal law, the owner may in this manner install dark tinting material regardless of whether the installation adversely affects the light transmittance. Individual States govern the operational use of vehicles by their owners and therefore it is within the authority of the States to preclude owners from applying dark tinting material on their vehicles.; I hope this information is helpful to you. Sincerely, Jeffrey R. Miller, 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.