Proposal to establish a new supplement to UN Regulation No. 179, improving and correcting brake emissions measurement procedures for light-duty vehicles of categories M₁ and N₁. The regulation applies full-friction braking testing on brake dynamometers using the WLTP-Brake cycle comprising ten trips and 303 brake deceleration events. Testing includes three sections: cooling air adjustment, brake bedding with five cycle repetitions, and emissions measurement with three cycle repetitions. Compliance is demonstrated by measuring PM10 and SPN10 emissions from brake corner emission family parents, with whole-vehicle emissions calculated using friction braking share coefficients specific to vehicle electrification types. PM10 limits are 3 mg/km for M₁/N₁ vehicles and 5 mg/km for N₁ Class III/N₂ vehicles. Conformity of production requires annual testing of brake corner emission families with statistical evaluation per decision charts through 31 December 2029 (Phase I, PM10 only), with Phase II from 1 January 2030 evaluating both PM10 and SPN10. A version of this document with tracked changes is available.