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: nht90-1.17OpenTYPE: INTERPRETATION-NHTSA DATE: JANUARY 16, 1990 FROM: SATOSHI NISHIBORI -- VICE PRESIDENT, INDUSTRY-GOVERNMENT AFFAIRS TO: ROBERT F. HELLMUTH -- DIRECTOR, OFFICE OF VEHICLE SAFETY COMPLIANCE, NHTSA TITLE: NEF-31 GEN/NCI 3092 ATTACHMT: ATTACHED TO LETTER DATED 3-15-90 TO SATOSHI NISHIBORI FROM STEPHEN P. WOOD; [A35 REDBOOK; STD. 120] TEXT: This responds to your October 31, 1989, letter regarding the compliance of 1989 Nissan pickup trucks with FMVSS 120. In my December 19th letter to you, I confirmed an extension until January 16, 1990, to respond to your request. Nissan's responses to your questions regarding the 1989 Nissan truck are set forth in the Attachment. We wish to emphasize, however, that, based on our reading of FMVSS 120, it is not clear that the vehicles in question fail to comply with that stand ard. Nissan has followed a procedure whereby tire inflation pressures specified on FMVSS 120 tire/rim information labels are determined based on the tire's ability to support their share of the vehicle's gross axle weight rating (GAWR). The load carryi ng capacity of the tires at various pressures is determined by reference to data in tire industry standarization manuals; such as the Tire and Rim Association (TRA) Yearbook. Once a minimum pressure that is adequate to carry the GAWR is determined, Nissa n considers other factors, such as vehicle ride characteristics, to select the recommended pressure. This process results in the selection of a recommended pressure that will permit the tires to carry safely GAWR loads and will provide good vehicle ride characteristics. Nissan believes that the procedure it followed resulted in the recommendation of a tire pressure that is consistent with safe vehicle operation and is permitted under FMVSS 120. Based on our reading of the Agency contractor's test report on this matter, it appears that the contractor has interpreted FMVSS 120 in a manner different from Nissan. However, we believe that our own reading of FMVSS 120 is consistent with the langu age used in that standard. In particular, based on our reading, we conclude that: 1. the tire label need not show the tire's maximum inflation pressure; and 2. the 1.1 adjustment factor in section 5.1.2 of the standard applies for tire selection purposes only. Nothing in FMVSS 120 requires that the relationships between tire inflation pressure and load, as specified by tire manufacturers in standardizat ion manuals or otherwise, must be universally adjusted by use of this factor. We read FMVSS 120 to require, in practical terms, that when a passenger car tire is to be used on a truck, a slightly larger capacity tire must be selected than would be the c ase if the tire were to be used on a similar size passenger car. Based on Agency statements in Federal Register notices regarding FMVSS 120, the standard apparently requires this difference in tire selection due to the greater potential for off-road use and heavy load operation (perhaps above the vehicle's rated load capacity) for trucks than for passenger cars, and not due to any inherent difference in load-pressure relationships for the vehicles. It is our understanding that the Agency's test report concludes that the 1989 Nissan truck that was inspected by the Agency's contractor does not conform to S.5.3.5 of FMVSS 120. Section 5.3.5 specifies that the vehicle's tire/rim selection label mus t show the "cold inflation pressure for [the] tires". This provision does not specify how the "cold inflation pressure" is to be determined, or for which driving conditions the pressure must be appropriate. FMVSS 120, as originally proposed, specified t hat the label must show the "maximum cold inflation pressures of the tires with which the vehicle is equipped, as marked on the tires. . ." See 36 Federal Register 14273-4, August 3, 1971, emphasis added. In a subsequent proposal, the requirement was re vised to specify that the label must show the "maximum tire inflation pressure", deleting the reference to the tires actually on the vehicle at the time of sale. See 39 Federal Register 19505, 19507, June 3, 1974. This revision was made to recognize and continue to permit the practice of dealers changing tire sizes prior to delivery of trucks to the purchaser. 39 Federal Register 19505. The final rule establishing FMVSS 120 adopts the current language of section 5.3.5 (as paragraph 5.3(c)), i.e., "cold inflation pressure", but the preamble does not explain the deletion of the term "maximum" with regard to the inflation pressure. See 41 Federal Register 3480, January 23 1976. Nevertheless, the change in wording suggests that the tire label must reflect some pressure other than the maximum pressure. We believe that the context of section 5.3.5 may provide some additional guidance as to which pressure must appear on the label. Section 5.3.1 specifies that the information required under section 5.3.3 through 5.3.5 must appear either "after each GA WR" in the case of a certification label or must be "appropriate for each GVWR-GAWR combination", if a combined certification/120 label format is used. Thus, the "cold inflation pressure" selected should be consistent with the GAWR of the vehicle. This conclusion is supported by a subsequent NHTSA preamble, which states that the section 5.3.5 pressure need not be the maximum pressure, "but, the pressure specified by the tire manufacturer as sufficient to carry the load specified by the vehicle manufac turer as the tire's share of the assigned GAWR". 42 Federal Register 7143, February 7, 1977. The 1989 Nissan truck inspected by the Agency is equipped with Firestone WR-12, P 195/75R14 M+S tires. The tires have a maximum load rating of 1400 pounds. The certification label on the vehicle specifies a cold inflation pressure of 34 psi for the rear tires and a GAWR of 2544 pounds for the rear axle. The key issue raised by NHTSA is whether the 34 psi pressure on the label is a pressure "specified by the tire manufacturer as sufficient to carry" half the GAWR, or 1272 pounds. The regulations do not specify a procedure by which the tire manufacturer must articulate whether the tire, inflated to 34 psi, will support a 1272 pound load. For example, we believe this information could be obtained from tire industry standardizat ion manuals or from direct discussions between the vehicle and tire manufacturers. Data in the 1989 Tire and Rim Association (TRA) yearbook show that the tires in question will support a load of 1279 pounds at 29 psi, with higher loads supportable at higher pressures. Therefore, the 1989 Nissan truck would appear to comply with sec tion 5.3.5. Moreover, the manufacturer of the tires used as original equipment on the vehicle has confirmed that the tires inflated to 34 psi, will carry 1383 pounds (which is more than half the GAWR) on this vehicle (see Enclosure 1). However, NHTSA has apparently interpreted the required calculation procedure differently. As we understand the procedure used by NHTSA's contractor in its test report, it first calculated a "tire load limit" at 34 psi by interpolating between the loa d limits at 32 psi and at 35 psi, as specified in the TRA tables. Assuming that a linear interpolation is appropriate, the 34 psi maximum load would be 1381.67 pounds. NHTSA's contractor then proceeds to divide the interpolated load by 1.1, yielding 125 6.06 pounds. Since this figure is less than the tire's share of the GAWR (1272 pounds), the contractor concludes that a violation has occurred. Assuming that linear interpolation between the table values is appropriate and the contractor's procedure is correct, a pressure of 34.956 pounds would be required to support 1272 pounds. We believe that the procedure followed by the contractor is not specified in FMVSS 120. In particular, we object to the contractor's application of the 1.1 adjustment factor to intermediate tire loads and for purposes other than tire selection, since the standard does not specify these procedures. The use of a 1.1 factor is specified in section 5.1.2 of the standard for tire selection purposes. That section provides that the sum of the load ratings of the tires fitted to an axle must be not less than the GAWR. Prior to calculating the sum, th e tire's load rating shall be reduced by dividing by 1.1 if the tire is listed in Appendix A of Standard 109 and is installed on a truck, bus, MPV, or trailer. However, no specific tires are listed in Appendix A of Standard 109. It is our understanding that prior to the early 1980s, that Appendix did list certain tire sizes for use on passenger cars. Therefore, section 5.1.2 may suggest that when passenger tires are used on trucks, the tire's load rating must be reduced by the 1.1 factor prior to det ermining whether the tires are adequate to support the GAWR. According to the 1977 preamble, the purpose of applying the 1.1 factor is "to account for the generally harsher treatment (impulse and surge loading in the case of MPV's off-road) to which the tires of a vehicle other than a passenger car are exposed that is not accounted for in passenger car tire rating". Supra. Thus, it appears that the purpose for the 1.1 factor is not to deal with a difference in the ability of a tire to support a given load at a particular pressure when the tire is used on a car as compared to use on a truck. Rather, the stated intent seems to be to deal with the greater off-road use (or possibly more frequent overload situations) to which vehicles other than passeng er cars are subjected. n1 n1 It is important to note that the 1989 Nissan truck meets the tire selection criteria of section 5.1.2. If the tires' maximum load rating (1400#) is divided by 1.1, and the adjusted sum (2545#) of the two tires' load ratings exceeds the GAWR (2544# ). The use of the 1.1 factor for tire selection purposes only is also suggested by the language of section 5.3.3. That provision references section 5.1.2 (and, thereby, the 1.1 factor) in determining whether the tire size is appropriate for the GAWR. H owever, the absence of the parenthetical reference to section 5.1.2 in section 5.3.5 suggests that the application of the 1.1 factor is not required for determining whether the tire pressure on the label is appropriate for the GAWR. To summarize, the language used in FMVSS 120 to describe the process to be used in determining the cold inflation pressure under section 5.3.5 is ambiguous at best, and contrary to the procedure used by NHTSA's contractor at worst. These deficiencies are exhibited with regard to the following determinations: 1. Whether the 1.1 adjustment factor is to be used for purposes other than tire selection; 2. Which tires are subject to the 1.1 factor (Appendix A, standard 109); 3. The source of information on the tire manufacturer's load limit for the tire, at various pressures; and 4. The procedure for interpolating information derived from the TRA tables. Of these factors, we believe the first to be the most significant, but all contribute to the ambiguity of the standard. It is our understanding that at least one other vehicle manufacturer has interpreted section 5.3.5 in a manner inconsistent with NHTSA's contractor. This suggests that a problem may exist with the wording of the standard and that more is involved than a single party's misreading of clear regulatory language. If the contractor's interpretation were the only acceptable interpretation, approximately 700,000 Nissan vehicles produced as far back as 1983 could be implicated (see Attachment). Response 5 in the Attachment lists additional vehicle/tire combinations where Nissan's specified tire pressure differs from that determined under the contractor's procedure. Nissan is now conducting additional tests to verify that these tires will su pport higher test loads. We expect that the results of this testing will demonstrate that the tires used on Nissan's vehicles have sufficient load capacity to support their share of the vehicles' GAWR at the recommended inflation pressures. The procedure being followed involves testing the tires to FMVSS 109 procedures, but increasing test loads by multiplying them by an overload f actor. The overload factor is calculated by multiplying the GAWR by 0.5 and dividing the product obtained by the tires' load rating at the pressure shown on the vehicle's tire label (calculated according to NHTSA's contractor's procedure, i.e., using th e 1.1 factor). The results of this testing should be available by January 31st. However, one of the affected tires (7.00 x 14) is no longer in production; therefore, a special batch of those tires is being produced. The test results for this one tire size should b e available by mid-February. Nissan wishes to work cooperatively with NHTSA to resolve this matter. However, we believe that the language of section 5.3.5 does not clearly provide a basis for finding the 1989 Nissan truck to be in noncompliance, or for conducting a notification a nd remedy campaign under the the Safety Act. We request that NHTSA consider the issues raised above and the results of our ongoing testing, and that the Agency concur that the Nissan vehicles comply with FMVSS 120. We request the opportunity to meet with you after you have considered the matter s raised in this letter, so that we can answer any questions you may have and discuss a resolution of the matter. If you have any questions regarding this matter, please contact Mr. Kazuo Iwasaki of my staff, at 202/466-5284. Sincerely, ENC. |
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ID: nht79-3.9OpenDATE: 11/14/79 FROM: AUTHOR UNAVAILABLE; Frank Berndt; NHTSA TO: Volvo of America TITLE: FMVSS INTERPRETATION TEXT: This is in response to the questions that you addressed to Mr. Hugh Oates over the telephone with regard to auxiliary fuel tanks. I have enclosed a copy of a letter which was sent to a company that planned to manufacture auxiliary fuel tanks for passenger cars and to do some installation. The principles enunciated in that letter are applicable to auxiliary fuel tanks intended for use in all types of motor vehicles except motor carriers in interstate commerce. If you have any further questions after reading the enclosed letter please feel free to contact Ms. Debra Weiner of my office who is familiar with the issues arising from the manufacture and use of auxiliary fuel tanks. |
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ID: nht93-5.46OpenTYPE: Interpretation-NHTSA DATE: August 4, 1993 FROM: Toshi Tanaka -- General Manager, Sales & Marketing Dept., Sensor Technology Co., Ltd. TO: Delmas Johnson -- FARS Program Manager, Office of Crashworthiness Research, Research and Development, NHTSA TITLE: Ref. No. TSX-242 ATTACHMT: Attached to letter dated 11/5/93 from John Womack to Toshi Tanaka (A41; Std. 208) TEXT: Could you please let me know of the followings for our understanding on FMVSS 208? 1. Is it true that the belt fastening law now goes into a part of the federal law? 2. Is it true that the cars with airbag do not need to perform "Roll Over Test"? I am looking forward to receiving your repy by return.
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ID: nht93-2.22OpenDATE: March 21, 1993 FROM: Christopher Banner TO: John Wolmack (Womack) -- NHTSA TITLE: None ATTACHMT: Attached to letter dated 7-9-93 from John Womack to Christopher Banner (A41; Part 568; Part 571.7(e)) TEXT: I am looking into the possibility of producing a line of luxury cars and limousines based on an existing chassis but having a body of my own making. I am sure that the Department of Transportation has all sorts of safety and other regulations which would cover such a product. Representative Jim Slattery of Kansas recommended you as a source of information on this subject. Could you either send me relevant material, or direct me to a source? Here in Manhattan, we have a government documents section in the Kansas State University Library. Perhaps I could find the references of interest in it, if I knew what they were. |
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ID: nht73-3.42OpenDATE: 03/08/73 FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA TO: Wiggins & Christian TITLE: FMVSR INTERPRETATION TEXT: This is in response to your letter of February 27, 1973, concerning the application of the new Federal Odometer Disclosure Requirements to transfers between dealers. The Federal requirements apply, with certain exceptions, to each transfer of ownership of a motor vehicle. Some types of vehicles, such as heavy trucks and antique vehicles, are exempt. Passenger cars and lighter vehicles, however, are exempted only in the case of transfers of new vehicles from a manufacturer or a distributor to a dealer or from one dealer to another. The transfer of a used car or light truck, whether from dealer to dealer, dealer to wholesaler, or dealer to customer, must be accompanied by a disclosure statement. ENC. |
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ID: nht93-6.30OpenDATE: September 2, 1993 FROM: John M. Tolliday -- President, Dayman USA, Inc. TO: John Womack -- Acting Chief Counsel, N.A.H.T.S.A. (NHTSA) TITLE: None ATTACHMT: Attached to letter dated 3/16/94 from John Womack to John M. Tolliday (A42; Part 591 Sec 102(3); Also attached to letter dated 8/7/89 from Stephen P. Wood to Clifford Anglewicz (Sec 102) TEXT: We are hoping to import into the United States British Army Ferret Armored Cars of which I enclose two photos. These vehicles were manufactured around 1970. They are in a driveable condition, but all armaments have been removed. I would be selling these on the basis they would only be used for off road purposes. If we did import these vehicles would they be exempt from Federal Motor Vehicle Standards? Thanking you in advance for your assistance. |
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ID: nht93-7.52OpenDATE: November 4, 1993 FROM: John Womack -- Acting Chief Counsel, NHTSA TO: John B. Walsh -- Legal Affairs Manager, American Suzuki Motor Corporation TITLE: None ATTACHMT: Attached to letter dated 10/29/93 from John B. Walsh to John Womack (OCC-9263) TEXT: This acknowledges receipt of your letter dated October 29, 1993, requesting an interpretation of the labeling requirements of the recent final rule mandating the installation of air bags in passenger cars and light trucks (58 FR 46551, September 2, 1993). As you suggested in your letter, we believe it would be appropriate to respond to your request in the notice responding to the petitions for reconsideration of the September 2 final rule. If you have any other questions, please contact Mary Versailles of my staff at this address or by phone at (202) 366-2992. |
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ID: 9263Open John B. Walsh Dear Mr. Walsh: This acknowledges receipt of your letter dated October 29, 1993 requesting an interpretation of the labeling requirements of the recent final rule mandating the installation of air bags in passenger cars and light trucks (58 FR 46551, September 2, 1993). As you suggested in your letter, we believe it would be appropriate to respond to your request in the notice responding to the petitions for reconsideration of the September 2 final rule. If you have any other questions, please contact Mary Versailles of my staff at this address or by phone at (202) 366-2992. Sincerely,
John Womack Acting Chief Counsel ref:208 d:11//4/93 |
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ID: nht72-1.8OpenDATE: 04/11/72 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: GGO Group, Inc. TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of April 3, 1972, to Mr. Schneider asking whether your Gemini Tow Control System would come under our regulations, and whether you would be considered a brake manufacturer. The Federal motor vehicle safety standard covering vehicle hydraulic brake systems, Standard No. 105, applies only to passenger cars (not directly to equipment manufacturers), and does not cover the hydraulic braking relationship between towing and towed vehicles. For that reason the Gemini system would not be regulated by Standard No. 105. There are no Federal standards applicable to a tow control system per se. We would, however, view you as a "manufacturer," and the product you have described as "motor vehicle equipment," within the remaining of the National Traffic and Motor Vehicle Safety Act of 1965. |
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ID: nht73-4.33OpenDATE: 07/17/73 FROM: AUTHOR UNAVAILABLE; Lawrence R. Schneider; NHTSA TO: Volvo of America Corporation TITLE: FMVSR INTERPRETATION TEXT: This is in reply to your letter of July 11, 1973, asking for a waiver of 49 CFR @ 575.6(c) with respect to consumer information that Volvo of America would like to supply to prospective purchasers of 500 passenger cars beginning July 30, 1973. There is no provision in the Consumer Information Regulations empowering the Administrator to waive the 30 day requirement and therefore we are unable to grant this request. We do not view the lack of this authority as unjust, given the purpose of the requirement "so that there may be an evaluation and dissemination to the public of this information if deemed appropriate" (34F.R.11501). We received your material on July 12, and the 30 day period will expire on August 11. |
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.