Interpretation ID: 2351y
Nissan Research & Development, Inc.
750 17th Street N.W., Suite 902
Washington, D.C. 20006
Dear Mr. Nishibori:
This responds to your January 16, 1990 letter to Mr. Robert Hellmuth, the Director of this agency's Office of Vehicle Safety Compliance, seeking an interpretation of Standard No. 120, Tire Selection and Rims for Motor Vehicles Other Than Passenger Cars (49 CFR 571.120). Specifically, S5.1.2 of Standard No. 120 provides that when a passenger car tire is used on vehicles other than passenger cars, the tire's load rating shall be reduced by dividing it by 1.10 before calculating the sum of the load ratings of all of the original equipment tires on the vehicle. S5.3.2 through S5.3.5 establish requirements for certain information about the tires and rims to be labeled on the vehicle. S5.3.2 sets forth lettering size and format requirements for the labeling. S5.3.3 through S5.3.5 require the labeling to provide the following information: the "size designation of tires....appropriate (as specified in S5.1.2) for the GAWR" be given on the label; the size and type designation of rims "appropriate for those tires", and the "cold inflation pressure for those tires".
Your question was whether the cold inflation pressure set forth on the label in response to S5.3.5 of Standard No. 120 must reflect the 1.1 reduction factor set forth in S5.1.2 for passenger car tires. You suggested in your letter, and in your January 18, 1990 meeting with agency staff, that S5.3.5 does not require the 1.1 reduction factor to be taken into account when determining the cold inflation pressure to be specified. Instead, you suggested that Standard No. 120 requires the vehicle manufacturer to specify an inflation pressure that is adequate to support the tire's share of the gross axle weight rating (GAWR), without regard to the 1.1 reduction factor. I cannot agree with your suggested interpretation.
You asserted that S5.3.5 merely requires the label to include the "cold inflation pressure for those tires," without referring to S5.1.2 and its 1.1 reduction factor. You contrasted this requirement with that in S5.3.3, which expressly refers to S5.1.2 and the 1.1 reduction factor. You asserted that this difference in wording showed that the 1.1 reduction factor need not be considered when specifying the cold inflation pressure on the label in response to S5.3.5. This argument is not persuasive.
The load-carrying capability of a tire generally varies with the inflation pressure of that tire; i.e., a tire can carry a greater load at a higher inflation pressure and a lesser load at a lower inflation pressure. Hence, a reference to inflation pressure alone, without any corresponding load-carrying capability to which that inflation pressure applies would be meaningless. If S5.3.5 of Standard No. 120 were interpreted to require the manufacturer to specify some inflation pressure, without regard to any load that must be borne by the tire at that inflation pressure, the vehicle manufacturer could specify an extremely high or low inflation pressure. Such a specification would be useless or even dangerous for the consumer, and contrary to the purposes of the labeling requirements.
You implicitly recognize that such an interpretation is unacceptable when you argue on page 1 of your January 16, 1990 that S5.3.5 of Standard No. 120 must be interpreted to require the manufacturer to recommend an inflation pressure "that will permit the tires to safely carry Gross Axle Weight Rating loads and will provide good vehicle ride characteristics." In other words, Nissan agrees that the inflation pressure specified in response to S5.3.5 cannot be an extreme value such as 1 psi; instead, it must be determined with reference to some load that the tires will carry.
The question then becomes what loading must be considered to determine if the specified inflation pressure complies with S5.3.5. This question is answered by reading the labeling requirement of S5.3.5 in connection with the other labeling requirements in S5.3, instead of considering S5.3.5 in a vacuum. S5.3.2 sets forth the format and lettering size for the labels to be placed on all vehicles manufactured on or after December 1, 1984. The information that must appear on such labels is set forth in S5.3.3, S5.3.4, and S5.3.5 of Standard No. 120. S5.3.3 specifies that the label shall include information on "the size designation of tires (not necessarily those on the vehicle) appropriate (as specified in S5.1.2) for the GAWR." (Emphasis added). On any reading of this emphasized language, it is beyond dispute that the 1.1 reduction factor set forth in S5.1.2 must be considered when specifying the appropriate tire size designation pursuant to S5.3.3. Following this, S5.3.4 requires information on the size and type designation of rims "appropriate for those tires" to appear on the label. The reference to "those" tires in S5.3.4 indicates that the tires are the tires previously specified in S5.3.3. Similarly, when S5.3.5 requires the cold inflation pressure for those tires to appear on the information label, the language is referring back to the tires specified in S5.3.3. Since NHTSA agrees with your statements that S5.3.3 incorporates the 1.1 reduction factor of S5.1.2 to determine compliance with S5.3.3, and since S5.3.5 refers to the tires specified in S5.3.3, the 1.1 reduction factor set forth in S5.1.2 must be considered to determine ocmpliance with S5.3.5 of Standard No. 120.
Sincerely,
Stephen P. Wood Acting Chief Counsel /ref:120 d:3/l5/90