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 |
|---|---|
ID: aiam3386OpenMr. Kenneth C. Lenz, Jr., Hendrickson Mfg. Co., Mobile Equipment Division, 8001 West 47th Street, Lyons, IL 60534; Mr. Kenneth C. Lenz Jr. Hendrickson Mfg. Co. Mobile Equipment Division 8001 West 47th Street Lyons IL 60534; Dear Mr. Lenz: This responds to your November 25, 1980, letter asking whether an safety standards have been violated by a truck modification that you perform. In your modification, you alter a chassis to provide right-hand controls. The vehicle is then sent to a final-stage manufacturer for completion.; As an incomplete vehicle manufacturer, you are required to attach th appropriate label to the vehicle in accordance with Part 567, *Certification*. That label makes certain statements about the compliance of the vehicle with safety standards as a result of your modifications.; You ask whether any safety standards have been violated by you modifications. It is impossible for the agency to determine compliance without testing one of your vehicles. You list several changes that you make to the vehicle, including the addition of: a foot throttle, foot service brake, hand spring brake, turn signal, transmission selector, and steering wheel. The agency has safety standards that govern many of these devices. These standards are found in Volume 49 of the Code of Federal Regulations, in Part 571. It is a manufacturer's responsibility to ensure that its vehicles comply with these standards. The only advice that we can offer is that nothing precludes the type of modifications that you propose. The installation of right-hand controls is permissible as long as the compliance with all safety standards is maintained.; Sincerely, Frank Berndt, Chief Counsel |
|
ID: aiam4443OpenMr. Toshio Maeda Executive Vice President & Chief Operating Officer Nissan Research & Development, Inc. P.O. Box 8650 Ann Arbor, Michigan 48104; Mr. Toshio Maeda Executive Vice President & Chief Operating Officer Nissan Research & Development Inc. P.O. Box 8650 Ann Arbor Michigan 48104; Dear Mr. Maeda: This is in reply to your letter of June 30, 1987 asking for an interpretation of paragraph S4.1.1.36(b)(3) of Motor Vehicle Safety Standard No. 108. That paragraph specifies in pertinent part that a replaceable bulb headlamp shall be designed to conform to Section 6.1-Aiming Adjustment Test, of SAE Standard J580 AUG79 Sealed Beam Headlamp Assembly. Section 6.1.1 states that 'when the headlamp assembly is tested in the laboratory, a minimum aiming adjustment of +/-4 deg. shall be provided in both the vertical and horizontal planes.' You have asked whether the aiming adjustment is to be achieved by the headlamp assembly, or by both the headlamp assembly 'and by the headlamp when it is mounted on the vehicle.' SAE J580 applies to the design of headlamp assemblies, including the functional parts other than the headlamps, such as aiming and mounting mechanisms and hardware. The assembly may include one or more headlamps. Although the headlamp assembly is tested in the laboratory, its design must be identical to the headlamp assembly used on the vehicle. Thus, if the aiming adjustment requirement is met by the headlamp assembly in the laboratory, it should also be met when the assembly is installed on the vehicle. An individual headlamp installed on the vehicle need not meet the aiming adjustment test unless that headlamp is part of a headlamp assembly comprising only one headlamp. I hope that this answers your question. Sincerely, Erika Z. Jones Chief Counsel; |
|
ID: aiam0953OpenFiles; Files; Your memorandum of November 27, 1972, concerning non-tabulated value for tire inflation pressures.; In response to the above-captioned memorandum, we, in coordination wit the Chief Counsel's Office, have concluded that Standard No. 110 does not preclude the use of odd-numbered tire inflation pressures on the placard required by S4.3 of Standard No. 110, and that the standard does not prohibit interpolation of the load values of the Standard No. 109 tables for purposes of compliance testing.; The relevant language of Standard No. 110 is in paragraph S4.3 an S4.3.1:; >>>S4.3 *Placard*. A placard, permanently affixed to the glov compartment door or an equally accessible location, shall display the --; (c) vehicle manufacturer's recommended cold tire inflation pressure fo maximum loaded vehicle weight and, subject to the limitations of S4.3.1, for any other manufacturer-specified vehicle loading condition...; S4.3.1 No inflation pressure other than the maximum permissibl inflation pressure may be specified unless --; (b) The vehicle loading condition for that pressure is specified, and (c) The tire load rating from Table I of S571.109 for the tire at tha pressure is not less than the vehicle load on the tire for that vehicle loading condition.<<<; There is nothing in the standard which specifically required th inflation pressure to be one actually listed (even-numbered) in the Tables of Standard No. 109. While paragraph S4.3.1(c) of Standard NO.(sic) 110, in referring to the load rating found in the table, arguably implies such a requirements, we cannot, without more specific language, read into the standard that recommended inflation pressures must be even-numbered. The mere fact that the specific tire load rating will not be printed in the table, however, does not preclude enforcement of the placard requirement. Because interpolation of values in a table is accepted engineering practice, we conclude that it is reasonable to interpolate such values in the Tables of Standard No. 109, for purposes of enforcing Standard No. 110, where manufacturers have specified odd-numbered inflation pressures.; Elwood T. Driver |
|
ID: aiam1641OpenMr. M. J. Denholm, Director of Engineering, Power Controls Division, Midland-Ross Corporation, 490 S. Chestnut Street, Owosso, MI 48867; Mr. M. J. Denholm Director of Engineering Power Controls Division Midland-Ross Corporation 490 S. Chestnut Street Owosso MI 48867; Dear Mr. Denholm: This responds to Midland-Ross' October 8, 1974, clarification of it February 8, 1974, petition for an amendment of S5.1.2.1 and S5.2.1.2 of Standard No. 121, *Air brake systems*, that would establish separate air reservoir volume requirements for several brake chamber types generally available in the air brake component market. You point out that Midland-Ross was referring to chamber stroke and not chamber diameter as the chamber dimension which could affect the safety of a brake system. You also requested that we adopt SAE Standard J10b instead of J10a as our specification of a reservoir that 'withstands' certain internal hydrostatic pressure.; In our denial of your petition, we did understand your point tha additional stroke could be discouraged by a reservoir capacity requirement based on chamber size at maximum travel of the piston or diaphragm. We found that the stopping distance requirements in effect mandate the installation of high performance components, and we do not anticipate a safety problem. If a safety problem does arise in the future, we would consider a modification of S5.1.2.1 and S5.2.1.2.; SAE Standard No. J10b is identical to J10a in its requirement that n rupture or permanent circumferential deformation of the reservoir exceed one percent. Therefore, for purposes of S5.1.2.2 and S5.2.1.3, we are adopting SAE J10b as our specification of 'withstand' until we undertake further rulemaking.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
|
ID: aiam1354OpenMr. Jack R. Gilstrap, Southern California Rapid Transit District, 1060 South Broadway, Los Angeles, CA 90015; Mr. Jack R. Gilstrap Southern California Rapid Transit District 1060 South Broadway Los Angeles CA 90015; Dear Mr. Gilstrap: We are enclosing an Experimental Device Permit authorizing you to equi the buses described in your letter of December 11 with a warning system which will flash the clearance and sidemarker lamps in the event of an emergency. The permit will expire on December 31, 1974.; Please supply us with the data on the number and types of crime involving your buses during the calendar years 1972 and 1973. This information can later be compared with that of similar periods during 1974 when the buses are equipped with the experimental lamps. We would also like to have a copy of the outline of your plan for evaluating the effectiveness of the new system.; A copy of the drawing or wiring diagram of the installation would als be of interest to us, particularly the safeguards taken against the possibility of inadvertent activation.; Very truly yours, Warren M. Heath, Commander, Engineering Section |
|
ID: aiam3369OpenMr. Stephen E. Mulligan, International Harvester, 401 North Michigan Avenue, Chicago, Il 60611; Mr. Stephen E. Mulligan International Harvester 401 North Michigan Avenue Chicago Il 60611; Dear Mr. Mulligan: This is in response to your letter of October 1, 1980, in which you as whether compliance with 49 CFR 567, Certification, will satisfy the requirements of S4.3 of Federal Motor Vehicle Safety Standard No. 115, 49 CFR 571.115.; Section 4.3 of Federal Motor Vehicle Safety Standard No. 115 require that the vehicle identification number (VIN) 'appear clearly and indelibly upon either a part of the vehicle other than the glazing that is not designed to be removed except for repair or upon a separate plate or label which is permanently affixed to such a part.' S4.3.1 requires each character to appear in a capital, sans serif typeface. In the case of passenger cars and trucks of 10,000 pounds or less GVWR, each character must have a minimum height of 4 mm. S4.4 specifies that the VIN for passenger cars and trucks of 10,000 pounds or less GVWR shall be located within to passenger compartment.; Section 567.4 of Part 567, Certification (49 CFR 567), requires tha the certification label be permanently affixed to the vehicle, and display the vehicle identification number. Consequently, for all vehicles except passenger cars and trucks of 10,000 pounds or less GVWR, compliance with S 567.4 of Part 567 would also effect compliance with S4.3 of Standard No. 115 so long as capital, sans serif typeface was used.; Sincerely, Frank Berndt, Chief Counsel |
|
ID: aiam2981OpenMr. Mark E. Grayson, E. Grayson, Executive Assistant for Government Affairs, National Tire Dealers & Retreaders Association, Inc., 1343 L Street, N.W., Washington, DC 20005; Mr. Mark E. Grayson E. Grayson Executive Assistant for Government Affairs National Tire Dealers & Retreaders Association Inc. 1343 L Street N.W. Washington DC 20005; Dear Mr. Grayson: This is in response to your letter of March 2, 1979, in which yo request clarification of several points relating to the Uniform Tire Quality Grading (UTQG) Standards (49 CFR 575.104), and the record retention requirements applicable to tire retreaders.; You inquire first as to the obligations of tire dealers under the UTQ regulation. As explained more fully in our recent letter to Mr. Tony Hylton of your organization, the UTQG regulation places the responsibility for supplying tire grading information on vehicle and tire manufacturers and tire brand name owners. These parties must make their own arrangements with tire distributors and dealers to assure that the required tire grading information reaches tire purchasers.; You ask whether bias-ply tires manufactured abroad prior to April 1 1979, but imported into the United States after April 1, must be labeled in accordance with the requirements of paragraph (d)(1)(i)(B) of the UTQG regulation (49 CFR 575.104(d)(1)(i)(B)). Paragraph (d)(1)(i)(B), which becomes effective on April 1, 1979 for bias-ply tires, applies to bias- ply tires manufactured after that date. The date of manufacture rather than the date of importation is controlling in determining whether tires fall within the tread labeling requirements of the UTQG regulation.; You also ask whether tires to which the UTQG labeling requirement apply can be imported into the United States without the required tread labels, provided adequate labels are attached at the tires' point of sale. The purpose of the UTQG labeling requirements is to provide information to assist consumers in tire purchasing decisions. Therefore, the tread labeling requirements of the regulation would be satisfied if labels are attached at the dealership prior to the time the tires are offered for sale. However, manufacturers and brand name owners should be cautioned that they will be held responsible should the dealer incorrectly label the tires or neglect to attach the required labels.; Finally, you inquire whether manufacturers of retreaded tires mus retain tire registration records compiled pursuant to Part 574, *Tire Identification and Recordkeeping* (49 CFR Part 574), in view of the recent exemption of retreaders from the registration requirements of that part. While the registration requirements of Part 574 no longer apply to the sale of retreaded tires, section 574.7(d) (49 CFR 574.7(d)) nonetheless requires that previously compiled records on retreaded tires be maintained for a period of not less than three years from the date the information was recorded by the tire manufacturer or his designee.; Sincerely, Frank Berndt, Acting Chief Counsel |
|
ID: aiam4156OpenMr. Rudy Valdez, Product Manager, Mr. Gasket Company, 19914 South Via Baron St., Compton, CA 90220; Mr. Rudy Valdez Product Manager Mr. Gasket Company 19914 South Via Baron St. Compton CA 90220; Dear Mr. Valdez: This is in reply to your letter of May 1, 1986, with reference t Federal Motor Vehicle Safety Standard No. 108 *Lamps, Reflective Devices, and Associated Equipment*.; Your first question concerns the liability of an aftermarket splas guard installed behind the rear wheels which would incorporate a decorative light, the illustration you enclose shows the word 'Ford' illuminated. Although the lighting equipment that is required by Standard No. 108 must be located on a rigid part of the vehicle, there is no such requirement for aftermarket equipment such as the device that you propose. If an item of aftermarket equipment is installed before the sale of a new vehicle to its first owner, such an item is permissible under Standard No. 108 provided that it does not impair the effectiveness of the required lighting equipment, but no matter when it is installed, it would be subject to regulation by any State in which a vehicle so equipped is registered or operated. We are not familiar with State laws on this subject, and recommend that you contact the Department of Motor Vehicles in States where you intend to sell your device.; Your second question asks for information on the new center hig mounted stop lamp, saying that you have seen some that do not appear to meet Federal requirements. You ask whether we will require retrofitting of vehicles. The new lamp was optional for passenger cars manufactured on or after August 1, 1984, and mandatory for those manufactured on or after September 1, 1985. The coverage of Standard No. 108 also extends to aftermarket items that are manufactured to replace original equipment center high mounted stop lamps, but there are no Federal requirements for lamps intended for use on cars that were not originally manufactured with them. We encourage manufacturers to meet the Federal specifications as closely as possible, however, and I enclose a copy of the regulation for your information. We have no authority to require retrofitting of vehicles.; I hope that this answers your questions. Sincerely, Erika Z. Jones, Chief Counsel |
|
ID: aiam3693OpenMr. Jerry G. Stapp, Jim Martin Tire, 522 Park Street, P.O. Box 2696, Jacksonville, FL 32203; Mr. Jerry G. Stapp Jim Martin Tire 522 Park Street P.O. Box 2696 Jacksonville FL 32203; Dear Mr. Stapp: This responds to your letter to Mr. Kratzke of my staff asking abou this agency's regulations applicable to regrooved tires. Specifically, you asked if a foreign casing must have a DOT symbol on the sidewall in order to be regrooved, what requirements apply to regrooved tires intended for a dealer's own use, and whether there are any restrictions on the use of regrooved tires in particular wheel locations.; 49 CFR Part 569 (copy enclosed) specifies the requirements which mus be met by all regrooved tires, except those intended solely for export and so tagged or labeled. The mechanics of importing casings for regrooving are explained in a previous letter of interpretation issued by the agency (copy enclosed). Once the casing is inside the customs territory of the United States, Part 569 specifies that the casing must be labeled 'regroovable' on both sidewalls. This marking cannot be added to the sidewall by a regroover before regrooving, but must have been placed there by the original manufacturer or a prior retreader. It seems unlikely that foreign manufacturers or retreaders would so label their tires. This means that few, if any, imported foreign casings may legally be regrooved. As explained in the enclosed letter, there is no requirement that the *DOT symbol* appear on the sidewall of casings in order for the casings to be regrooved.; The requirements of Part 569 apply to all tires regrooved in the Unite States, and apply equally to tires regrooved for sale to another party and to tires regrooved for the regroover's own use (Part 569.7). Each violation of those requirements could subject the offender to a $1,000 civil penalty. Each illegally regrooved tire would be treated as a separate violation.; With respect to your question about restrictions on the application an wheel position of a regrooved tire, this agency has no regulations. The bureau of Motor Carrier Safety of the Federal highway Administration has issued a regulation applicable to carriers used in interstate commerce. That regulation prohibits the use of regrooved tires above a certain load-carrying capacity on the front wheels of trucks and truck tractors. If you need further information concerning this subject, please contact Mr. Kenneth L. Pierson, Director, Bureau of Motor Carrier Safety, Federal Highway Administration, Washington, D.C. 20590.; Should you have any further questions regarding regrooved tires, pleas feel free to contact Mr. Kratzke at (202) 426-2292.; Sincerely, Frank Berndt, Chief Counsel |
|
ID: aiam0816OpenMr. Robert F. Farrelly, Safety Products, Inc., 331 East Brooks Road, Suite 11, Memphis, TN 38109; Mr. Robert F. Farrelly Safety Products Inc. 331 East Brooks Road Suite 11 Memphis TN 38109; Dear Mr. Farrelly: This is in reply to your letter of July 17, 1972, in which you as whether a person who installs on new vehicles a device you manufacture called the Safti-Stabilizer is required to recertify the vehicle.; A person will be required to recertify a new, completed vehicle if h modifies it is such a manner that he becomes a 'manufacturer' under the National Traffic and Motor Vehicle Safety Act. A person will be considered a manufacturer if the modifications he performs produce significant changes in the vehicle's configuration or purpose. while this determination is generally made on a case by case basis, examples of modifications which the NHTSA has considered to be 'manufacturing' include the addition of new axles, or the changing of a completed truck van into a motor home.; The NHTSA has taken the position, in close cases, that it will accept good-faith determination of a person modifying new vehicles as to whether the modification is of such a nature so as to make that person a manufacturer. Based on the information you have provided to us, it appears that the installation of the Safti-Stabilizer does not significantly change the vehicle's configuration or purpose. Consequently, we would accept a determination that the installation of the Safti-Stabilizer does not constitute remanufacturing, and a person who installs the device on new vehicles need not recertify them.; Yours truly, Richard B. Dyson, Assistant 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.