; and (5) by inserting after paragraph (19), as redesignated, the following: (20) trailer means a vehicle, with or without motive power, which is designed— (A) to carry persons or property; and (B) to be drawn by a motor vehicle. . 4. Underride guard rulemaking (a) In general Subchapter II of chapter 301 of title 49, United States Code, is amended by adding at the end the following: 30129. Underride guards (a) Rear 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 to require the installation of rear underride guards that meet the performance standards described in paragraph (2) on all trailers, semi-trailers, and single unit trucks with a gross vehicle weight rating of more than 10,000 pounds that are manufactured on or after the effective date of the rule. (2) Performance standards A rear underride guard shall be considered to meet the performance standard referred to in paragraph (1) if a passenger motor vehicle traveling at 35 miles per hour is prevented, as verified through crash testing while attached to a trailer, from moving underneath the rear of a trailer, semi-trailer, or single unit truck on which the rear underride guard has been installed after— (A) an impact in which the passenger vehicle impacts the center of the rear of the trailer, semi-trailer, or single unit truck; (B) an impact in which 50 percent the width of the passenger vehicle overlaps the rear of the trailer, semi-trailer, or single unit truck