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
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ID: aiam1840OpenMr. Curtis Eddy, Vice President - Engineering, Matlock Truck Body & Trailer Corp., P. O. Box 7385, Nashville, TN 37210; Mr. Curtis Eddy Vice President - Engineering Matlock Truck Body & Trailer Corp. P. O. Box 7385 Nashville TN 37210; Dear Mr. Eddy: This is to respond to your letter of February 11, 1975, to Mr. Wolfgan Reinhart, concerning your defect notification letter in NHTSA campaign No. 74-0203.; You believe that the second sentence in your notification lette properly determined that the defect existed in Matlock Model trailers. That sentence read, 'Matlock Truck Body and Trailer Corporation has determined that a defect which relates to motor vehicle safety exists in the brake shoes of Standard Forge axles with 12 1/4 and 7 1/2 brake shoes on Matlock Model MTE (electronic trailers).' The NHTSA has consistently viewed a determination stated in this manner as relating to equipment (brake shoes) and not specifically to the vehicle. Matlock's determination should have been that the defect had been determined to exist in the described vehicles. We are aware that the existing requirements (49 CFR S 577.4(b)(1)) are not worded as explicitly as they might be. However, a proposed amendment to Part 577 published November 25, 1974 (39 FR 41182), did attempt to clarify the intent of this section. Should you have need to issue defect notification in the future we would expect the statement of determination to be directed specifically at the vehicles you manufacture.; With respect to your second point, section 577.4(d) calls for th evaluation to mention the possibility of vehicle crash where that is a potential result of the defect. In that regard your notification was clearly deficient.; We hope that this clarifies our earlier letter to you. Please feel fre to write again if you have questions regarding the interpretation or application of any NHTSA requirements.; Yours truly, Andrew G. Detrick, Director, Office of Defect Investigation, Motor Vehicle Programs; |
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ID: aiam4711OpenMr. Michael S. Kmiecik 5601 Western Avenue Omaha, Nebraska 68132; Mr. Michael S. Kmiecik 5601 Western Avenue Omaha Nebraska 68132; "Dear Mr. Kmiecik: This is in reply to your letter with respect t vehicle modification kits you wish to purchase, to be used in conversion of Datsun 240-280Z cars from closed to open vehicles. You have asked for the safety standards that apply to l974-78 convertibles, and whether the conversion kit meets these standards. I regret the delay in responding. We appreciate your efforts to meet the requirements of the National Traffic and Motor Vehicle Safety Act. As you appear to realize, the Act requires, in essence, that vehicle alterations by a motor vehicle manufacturer, distributor, dealer or repair business must not render wholly or partially inoperative any device or element of design installed on that vehicle in accordance with a Federal motor vehicle safety standard. This means that a vehicle at the end of its conversion process must continue to meet the standards that applied at the time that it was first manufactured. This does not preclude conversions that render compliance with a standard physically impossible, obviously an open car cannot meet, for example, the standard for roof crush resistance (Standard No. 216), and convertibles, are, in fact, exempt from it. Such a conversion would allow substitution of a two-point (lap belt) restraint system in a convertible for a three-point (lap-shoulder belt) restraint system that may have been installed when it was a closed car (Standard No. 208). After the vehicle alterations are complete, the vehicle must conform to the barrier tests specified in several standards. We note that the items that comprise the kit are intended to add rigidity to the body and frame after removal of the top, but are unable to advise you of the effect these modifications would have upon the safety performance of the vehicle as converted. There are no Federal safety standards that apply to the individual items in your kit. The standards that apply to motor vehicles, including convertibles, manufactured from October 1, l973, through September 30, l978, will be found at Title 49 Code of Federal Regulations Part 571. Specifically, the standards appear in volumes titled 49 CFR Parts 200 to 999, revised as of October 1, l973, l974, l975, l976, and l977. Originally, these volumes were available through the U.S. Government Printing Office (which may have an Omaha outlet). If they are no longer available through the GPO, we recommend that you consult a local law library. Thank you for your interest in motor vehicle safety. Sincerely, Stephen P. Wood Acting Chief Counsel"; |
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ID: aiam1513OpenMr. Burt Weller, Engineering Manager, Truck Trailer Manufacturers Ass., 2430 Pennsylvania Avenue, N.W., Washington, DC 20037; Mr. Burt Weller Engineering Manager Truck Trailer Manufacturers Ass. 2430 Pennsylvania Avenue N.W. Washington DC 20037; Dear Mr. Weller: This is in response to your letter of May 29, 1974, concernin paragraph S5.3.2 of Federal Motor Vehicle Safety Standard No. 121, *Air brake systems*.; When a full trailer is tested for compliance with S5.3.2, the wheels o the steerable axle(s) cannot lock up at speeds above 10 mph except for controlled lockup of wheels allowed by an antilock system.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam4341OpenMr. R.O. Sornson, Director, Regulatory Research and Analysis, Chrysler Corporation, P. O. Box 1919, Detroit, MI 48288; Mr. R.O. Sornson Director Regulatory Research and Analysis Chrysler Corporation P. O. Box 1919 Detroit MI 48288; Dear Mr. Sornson: Thank You for your letter requesting an interpretation of the tes procedure used in the latchplate access test of Standard No. 208, *Occupant Crash Protection*. I regret the delay in our response. You specifically asked for an interpretation of the requirement of S10.6 of the standard that a vehicle's seat shall be placed 'in its forwardmost adjustment position' when determining whether a vehicle meets the latchplate reach requirements of S7.4.4 of the standard. You asked whether in conducting the test, Chrysler should move a manually adjusted bench or bucket seat to its forward seat track 'stop' and move a power bench or bucket seat to its 'full forward' and 'full down' position. As explained below, both a manually adjusted seat and a power adjusted seat should be moved to its full forward position or full forward seat track stop. However, S7.4.4 of the standard does not currently address how the seat is to be vertically adjusted. The agency has recently received a petition from the Motor Vehicle Manufacturers Association asking the agency to address the general issue of positioning adjustable power seats for the purposes of Standard No. 208. If the petition is granted, we will address the issue of vertical placement of the seat for the purposes of S7.4.4. In the interim, the agency will conduct its compliance testing for S7.4.4 in the following manner. The agency will first place the seat in the vertical adjustment position used by the manufacturer in its certification test. Then the agency will move the seat horizontally to its full forward position.; You noted that several of the comfort and convenience requirements o the standard specifically provide that a seat is to be moved to its full forward and full down position. For example S7.4.3, which sets out the belt contact force requirements, and S7.4.5, which sets out the safety belt retraction requirements, specifically provide that the seat is to be tested under the conditions of S8.1.2 of the standard. In turn, S8.1.2 provides that adjustable seats that are capable of vertical adjustment are to be placed in their lowest position.; However, the latchplate access requirements of S7.4.4 of the standar does not have a reference to positioning a seat in accordance with S8.1.2 of the standard. Instead, it specifies only that the seat shall be placed in its full forward adjustment position. Thus, in determining a seat's full forward position for the purposes of S7.4.4, the agency will follow the following procedure. Since the standard does not prescribe a vertical position for the seat, the agency will use the vertical position use by the manufacturer in its certification tests. The agency will then move a power seat horizontally to its full forward position.; If you have any further questions, please let me know. Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam3484OpenMr. D. R. Wachsmuth, Senior Test Engineer, Dayton T. Brown, Inc., Church Street, Bohemia, Long Island, NY 11716; Mr. D. R. Wachsmuth Senior Test Engineer Dayton T. Brown Inc. Church Street Bohemia Long Island NY 11716; Dear Mr. Wachsmuth: This responds to your recent letter requesting an interpretation o paragraph S4.4(b)(3) of Safety Standard No. 209, *Seat Belt Assemblies*, as it applies to a continuous-loop, Type 2 seat belt assembly. You ask whether each structural component of such a seat belt assembly should be considered 'common' hardware for both the pelvic and upper torso portions of the assembly.; Paragraph S4.4(b)(3) of Standard No. 209 specifies that the structura components in a Type 2 seat belt assembly that are common to pelvic and upper torso restraints shall withstand a force of not less than 3,000 pounds. Arguably, in a continuous-loop system with a sliding buckle latchplate, every since, as your letter points out, if one of the components should fail, the entire assembly could be rendered useless. However, the agency has stated in the past that testing for compliance with paragraph S4.4 of the standard on continuous- loop, Type 2 assemblies will be conducted by using a webbing clamp to segregate the portion of the assembly not being tested, i.e., to separate the pelvic and upper torso portions. This means that in continuous-loop assembly without the use of webbing clamps, the agency determined that such a test method is extremely difficult to perform. I am enclosing copies of two earlier letters of interpretation on this subject.; In light of this prior interpretation, the agency cannot conclude tha all components of a continuous-loop system are 'common' hardware for purposes of S4.4(b)(3). Rather, it is our opinion that only the latchplate, buckle and the inboard seat belt anchorage are common hardware for purposes of S4.4(b)(3). The belt retractor and the 'D' ring should be considered only part of the upper torso portion of the continuous-loop system.; I would point out that it is up to the vehicle manufacturer t determine and certify compliance with all applicable safety standards under the National Traffic and Motor Vehicle Safety Act. The agency does not provide prior approval of any safety design or test method. Therefore, you are free to test seat belt assemblies by any method you believe to be sufficient to establish due care that the assemblies are in compliance with Safety Standard No. 209. In our opinion, however, the test method mentioned in your letter would maintain a somewhat higher standard of performance than that currently required by the standard.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1143OpenMr. Donald W. Taylor, Volvo of America Corp., Rockleigh, New Jersey 07647; Mr. Donald W. Taylor Volvo of America Corp. Rockleigh New Jersey 07647; Dear Mr. Taylor: This is in reply to your letter of May 8, 1973, concerning the inten of section S4.7 of the amendment of Motor Vehicle Safety Standard No. 201 proposed by the notice of September 25, 1970. Although we have recently issued a notice advising the public that we intend to issue a further proposal on this subject before adopting a final rule, we can provide a brief explanation of the intent of Section S4.7.; The principal portions ofthe(sic) 'A' and 'B' pillars to which S4.7 wa directed, are those portions lying above the low line of the vehicle's window. However, the breadth of S4.7 is such that it would also include all contactable areas of the pillars lying below the window line.; You will have further opportunity to comment on the use of forc distributing materials and response to the rulemaking of Standard 201.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1456OpenMr. Bruce Caulkens, Bruce Caulkens, Inc., 28500 Hayes Avenue, Roseville, MI 48066; Mr. Bruce Caulkens Bruce Caulkens Inc. 28500 Hayes Avenue Roseville MI 48066; Dear Mr. Caulkens: This is in response to your letter of April 4, 1974 requestin information concerning the existence of any Federal Motor Vehicle Safety Standards applicable to auxiliary fuel tanks.; The National Highway Traffic Safety Administration has promulgated n motor vehicle safety standard relating to auxiliary fuel tanks. There is, however, a safety standard which imposes performance requirements upon motor vehicles with regard to their fuel systems. Thus if installation of the auxiliary tank is accomplished prior to the first purchase of the vehicle for purposes other than resale causing the vehicle's fuel system not to be in compliance with the applicable safety standard, the person installing the tank or offering the vehicle for sale would be in violation of S108(a)(1) of the National Traffic and Motor Vehicle Safety Act. That would make the installer or seller subject to civil penalties of up to $1,000 for each violation.; The National Traffic and Motor Vehicle Safety Act authorizes th Secretary of Transportation to make a determination as to whether or not an item of motor vehicle equipment contains a defect which relates to motor vehicle safety. If he finds that a safety-related defect exists, he may compel the manufacturer to notify purchasers of the hazard. Therefore, even though auxiliary fuel tanks are not the subject of a standard, they still must be safely designed.; For your information, I have enclosed a copy of the Federal Safet Standard relating to motor vehicle fuel systems.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3191OpenMr. John B. White, Engineering Manager, Technical Information Department, Michelin Tire Corporation, One Marcus Avenue, Lake Success, New York 11042; Mr. John B. White Engineering Manager Technical Information Department Michelin Tire Corporation One Marcus Avenue Lake Success New York 11042; Dear Mr. White: This responds to your November 16, 1979, letter in which you requeste an interpretation of the requirements of Federal Motor Vehicle Safety Standard No. 109 (49 CFR S571.109). Specifically, you asked if it is permissible for a tire manufacturer to label its tires with information about other tire sizes which the labeled tire could be used to replace. For example, you stated that Michelin would like to label its tires with the alphanumeric tire size which its P-metric tire sizes could replace and that Michelin would like to label its 230-15 tires as replacements for the 225-15 tires. Such labeling is expressly prohibited by Standard No. 109.; Paragraph S4.3(a) of Standard No. 109 specifies that each tire shall b labeled with '*one* size designation, except that equivalent inch and metric size designations may be used.' With respect to the alphanumeric sizes and the P-metric replacements and the 225-15 and 230-15 sizes, the suggested replacements sizes have different section widths and minimum size factors than the sizes they would be replacing. In other words, they are not equivalent size designations, and S4.3(a) prohibits the tire from containing more than one size designation in these circumstances.; Labeling of the sort you have requested has been commonly referred t as 'dual-size markings.' Dual-size markings are a representation that a particular tire can be considered as meeting fully the criteria of two separate tire size designations. In fact, such tires do not satisfy the physical dimension criteria in Standard No. 109 for both size designations. As a consequence, labeling of this type was specifically prohibited when the labeling requirements o Standard No. 109 were amended at 36 FR 1195, January 26, 1971. The prohibition has been repeated in subsequent notices which addressed the question of tire labeling under the Standard, *see* 39 FR 10162, March 18, 1974 and 42 FR 12869, March 7, 1977.; I should note that prohibition of dual-size markings does not mean tha NHTSA believes that the replacement tires would perform inadequately if installed on the rims. However, dual-size markings represent a marketing effort by tire manufacturers to attempt to persuade consumers to change the size and/or type of tires mounted on their cars. It is inappropriate to extend this marketing effort to the Federally required label on the tire. The manufacturer must provide the consumer, in a straightforward manner, technical information necessary for the safety of the consumer's automobile. This should be the only purpose of the label.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam4654OpenMr. Frank E. Timmons Deputy Director, Tire Division Rubber Manufacturers Association 1400 K Street, NW Washington, DC 20005; Mr. Frank E. Timmons Deputy Director Tire Division Rubber Manufacturers Association 1400 K Street NW Washington DC 20005; "Dear Mr. Timmons: This responds to your September 28, 1989 lette requesting that NHTSA reconsider its August 30, 1989 interpretation (copy enclosed) of the traction grading procedures of the Uniform Tire Quality Grading Standards ('UTQGS,' 49 CFR /575.104). In that earlier interpretation, the agency was asked by E.H. Galloway about the correct interpretation of the UTQGS provisions requiring one to 'inflate the tire to 24 psi, or, in the case of a tire with inflation pressure measured in kilopascals, to 180 kPa.' See //575.104(f)(2)(i)(B) and (D). Specifically, Mr. Galloway asked whether tires with inflation pressures expressed in both English units (psi) and metric units (kPa) should be inflated to 24 psi or 180 kPa during the testing to determine the tires' traction grades under the UTQGS. In its August 30 interpretation, the agency concluded that tires whose inflation pressure is expressed in both English and metric units should be inflated to 24 psi for the UTQGS traction testing. That interpretation explained its conclusion as follows: The language of the regulation sets forth a general requirement for an inflation pressure of 24 psi, and a subordinate requirement that 'tires with inflation pressure measured in kilopascals' use an inflation pressure of 180 kPa. An examination of the background of this language shows that the alternative inflation pressure of 180 kPa is to be used only for tire sizes that have inflation pressures specified only in kilopascals. Your letter asked that the agency reconsider this interpretation. You stated that P-metric tires generally are labeled with a maximum inflation pressure of 240 kPa. However, section S4.3.4(a) of Standard No. 109, New Pneumatic Tires - Passenger Cars sets forth an additional labeling requirement for tires whose maximum inflation pressure in expressed in kPa, as follows: 'If the maximum inflation pressure of a tire is 240, 280, 300, or 340 kPa, then each marking of that inflation pressure ... shall be followed by the equivalent inflation pressure in psi, rounded to the next higher whole number.' This requirement in Standard No. 109, therefore, prohibits any passenger car tire from being sold or offered for sale in this country with the inflation pressure specified only in kPa. By specifying conditions for use of the alternative inflation pressure of 180 kPa that are impossible for any tire to satisfy, because of the requirements of Standard No. 109, the effect of the August 30, 1989 interpretation is to remove the alternative inflation pressure from the UTQGS traction testing procedures. A correct interpretation of a regulation gives effect and meaning to all of the language in a regulation. For this reason, I believe the August 30, 1989 interpretation of the UTQGS traction testing procedures was incorrect. I conclude that any tire with its inflation pressure expressed first in metric units, with the equivalent pressure in English units shown in parentheses, is a 'tire with inflation pressure measured in kilopascals,' as that phrase is used in 49 CFR /575.104(f)(2)(i)(B) and (D). Accordingly, any such tire would be inflated to 180 kPa for UTQGS traction testing. I apologize for any confusion or inconvenience that might have been caused by the August 30 interpretation. Sincerely, Stephen P. Wood Acting Chief Counsel Enclosure cc: E. H. Galloway Uniform Tire Quality Grading Test Facility P.O. Box 1671 San Angelo, TX 76902"; |
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ID: aiam1006OpenMr. Carl Monk, 428 Southland Boulevard, Louisville, Kentucky 40214; Mr. Carl Monk 428 Southland Boulevard Louisville Kentucky 40214; Dear Mr. Monk: Dr. Brinegar asked that I review and respond to your letter of Decembe 23, 1972, regarding warning devices.; As you know from previous correspondence, the National Highway Traffi Safety Administration (NHTSA) issued a Notice of Proposed Rule Making on a standard for warning devices in November 1970. One of our major concerns in issuing this standard was the great variety of warning devices of all sizes, shapes, forms and configurations that were available to the motoring public. While many of these provided varying degrees of effectiveness, the great variety also created confusion and misunderstanding to the motoring public. Standardization of these devices was therefore of prime importance.; In response to this notice many comments, designs and recommendation were suggested for inclusion in the standard. All responses were carefully reviewed and evaluated before we issued the final rule in March 1972. Federal Motor Vehicle Safety Standard No. 125 represents an attempt to achieve a balance between many factors including shapes, size, cost, visibility, stability and weight. Since these triangle are designed for ultimate use in all kinds of vehicles, from passenger cars to heavy trucks, we had to be careful not to specify requirements that would put them beyond the reach of the average motoring public.; We are appreciative of your comments to the docket and your subsequen correspondence of the Department of Transportation, regarding the wind stability requirement of the device. Vehicles traveling at 70 mph do not create an effective wind velocity of 70 mph off the roadside. Research data shows that warning devices designed to withstand wind velocities of approximately 40 mph will be sufficient for the majority of wind conditions created by truck turbulence and atmospheric wind velocities without unnecessary penalties in weight and cost. However, Standard No. 125 will in no way restrict the manufacture and sale of devices with higher wind-resistance capabilities for special uses. These are *minimum* standards.; Again, we appreciate your interest in this aspect of motor vehicle safety. it is the ideas and opinions of concerned individuals, such as yourself, that enable us to ensure rules and regulations that are meaningful and worthwhile to the motoring public. Thank you for writing E.T. Driver, Director, Office of Operating Systems, Motor Vehicle Programs; |
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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.