; and (C) an impact in which 30 percent of the width of the passenger vehicle overlaps the rear of the trailer, semi-trailer, or single unit truck. (3) Retrofit requirements Not later than 2 years after the date of the enactment of this section, the Secretary shall issue a final rule requiring the installation of rear underride guards described in paragraph (1) on all trailers, semi-trailers, and single unit trucks with a gross vehicle weight rating of more than 10,000 pounds that are manufactured before the effective date of the rule required by paragraph (1). (4) Compliance dates (A) In general Except as provided in subparagraph (B), compliance with each of the rules issued by the Secretary under paragraphs (1) and (3) shall be required beginning 1 year after the date on which the final rule is published in the Federal Register. (B) Phase-in The Secretary may permit a phase-in period (not to exceed 2 years) for the installation of rear underride guards on trailers, semi-trailers, and single unit trucks described in paragraph (3). (b) Side underride guards (1) In general Not later than 1 year after the date of the enactment of this section, the Secretary shall issue a final rule requiring the installation of side underride guards that meet the performance standards described in paragraph (3) on all trailers, semi-trailers, and single unit trucks with a gross vehicle rating of more than 10,000 pounds manufactured on or after the effective date of the rule. (2) Retrofit requirements Not later than 2 years after the date of the enactment of this section, the Secretary shall issue a final rule requiring all trailers, semi-trailers, and single unit trucks with a gross vehicle rating of more than 10,000 pounds manufactured before the effective date of the rule required by paragraph (1) to be equipped with side underride guards that meet the performance standards described in paragraph (3). (3) Performance standards A side underride guard meets the performance standards described in this paragraph if the side underride