Interpretation ID: 2104y
Deputy Director, Tire Division
Rubber Manufacturers Association
1400 K Street, NW
Washington, DC 20005
Dear Mr. Timmons:
This responds to your September 28, 1989 letter 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
ref:109#575 d:ll/l/89