The EPA proposed this regulation on October 29, 1999, at 64 FR 58473. The proposal announced the opportunity for written public comment until December 2, 1999. The proposal also provided notice of a public hearings which was held on November 2, 1999 in Philadelphia, PA. On December 7, 1999, EPA reopened the comment period until December 16, 1999 for all issues in the proposal with the exception of the proposal to impose Tier 2 emission standards on passenger vehicles in the 8,501 - 10,000 pound GVWR range (64 FR 68310). Complete transcripts of the public hearing and the full text of each comment letter may be found in Docket No. A-98-32. All data and information relied upon by EPA in developing the regulation also may be found in Docket No. A-98-32. This docket is available for public inspection and copying between 8:00 a.m. and 5:30 p.m., Monday through Friday, excluding government holidays, at Room M-1500, Waterside Mall, 401 M Street, S.W., Washington, D.C. For Docket A-98-32, this document summarizes the written and oral comments submitted at the public hearing on November 2, 1999 (Docket Category IV-F), as well as the comment letters received during the public comment period (Docket Category IV-D), and records EPA's responses to those comments. In most cases in this document, EPA has listed all of the commenters who made a specific comment. In certain instances, however, the Agency may have identified one or a representative number of commenters. The reader should note that many of the most significant comments are also addressed in the preamble for the final rule and the responses in this document cross-reference the corresponding discussion in the preamble where appropriate. The responses presented in this document are intended (1) to augment the responses to comments that appear in the preamble to the final rule, or (2) to address comments not discussed in the preamble to the final rule. Although portions of the preamble to the final rule may be paraphrased in this and other documents where useful to add clarity to responses, the preamble itself remains the definitive statement of the basic rationale for the final rule. EPA received approximately 150 written comments. A copy of each comment letter received is included in the rulemaking docket. A list of commenters and the EPA docket item number assigned to their correspondence is also included in the docket. All of the comments have been carefully considered, and where determined to be appropriate, changes have been made in the final regulation. The comments were divided in to 28 general issue areas. Comments within a particular Issue (or Subissue) are divided into specific comments (such as "Comment A" or Comment "A.1"), so that comments and responses on specific aspects of an Issue (Subissue) are grouped together. The lettering and numbering of these comments preserves the Agency's internal classification of points raised on a particular issue in the various comment letters. This approach allows for crossreferencing between responses to related comments. In certain places, comments have been consolidated in a logical manner for the Agency's response. Even in these consolidated comments, the comment identification in this document preserves the Agency's internal lettering and numbering identification system within an issue (for instance a comment may be identified as "Comments A, F, G, N, and S" if those individual comments have a single consolidated response.