UN R141 — 01 series of amendments

The scope now adds categories M2, M3, N2, N3, O3 and O4 to M1 (up to 3,500 kg) and N1, when equipped with a TPMS. The scope no longer excludes vehicles fitted with dual wheels on an axle. Paragraph 5.1.1. no longer limits the performance requirements to vehicles with all axles equipped with single tyres. A “Twin wheel” is now defined as the fitment of a pair of wheels on one side of an axle, on the same hub. Tyres are classified as C1 (UN Regulation No. 30), or C2 or C3 (UN Regulation No. 54). If a variant submitted for approval is fitted with twin wheels, that variant must be used for the Annex 3 tests (paragraph 5.1.5.).

For M2, M3, N2, N3, O3 and O4, the system must operate from 30 km/h or below up to the vehicle's maximum design speed. Paragraphs 5.2.1. and 5.3.1. now apply to M1 (up to 3,500 kg) and N1 vehicles fitted with class C1 tyres. For M1 (up to 3,500 kg) and N1 with class C2 tyres, new paragraphs 5.2.2. and 5.3.2. use a minimum pressure of 220 kPa. New paragraphs 5.2.3., 5.2.4., 5.3.3. and 5.3.4. cover M2, M3, N2, N3, O3 and O4 vehicles fitted with class C2 or C3 tyres. In these paragraphs, the trigger is a 20 per cent reduction of the in-service operating pressure in a rolling tyre in contact with the ground. New paragraph 2.13. defines “Cumulative driving time” with speed thresholds of 40 km/h for M1 (up to 3,500 kg) and N1, and 30 km/h otherwise.

For M2, M3, N2, N3, O3 and O4, tests use 30 km/h to 90 km/h, or the maximum design speed if less than 90 km/h. In the learning/tyre warming phase, M2, M3, N2, N3, O3 and O4 vehicles are driven at least 120 minutes, averaging 60 km/h (±10 km/h). For M2, M3, N2, N3, O3 and O4, one deflation procedure deflates all tyres within 15 minutes of measuring the warm pressure. For M1 (up to 3,500 kg) and N1 with class C2 tyres, the test deflation uses a minimum pressure of 220 kPa. Before tyre inflation, M2, M3, N2, N3, O3 and O4 vehicles must stay stationary for at least 4 hours. If the vehicle is equipped with lift axle(s), they must be fully lowered so that the tyres have contact with the ground during testing.

New paragraphs 2.14. and 2.15. define the “Tyre Pressure Refill System (TPRS)” and the “Central Tyre Inflation System (CTIS)”. A TPRS or CTIS meeting the Annex 4 test criteria is deemed equivalent to a TPMS, and a TPMS is not required to be installed. To check the refill functionality, one tyre is deflated by 20% but not more than 50 kPa below the recommended cold inflation pressure (Prec). The TPRS or CTIS must start refilling within 2 minutes, and the refill process must be completed within 8 min after it has started. In the malfunction warning check, the manufacturer's optical signal for malfunction must be ON within 8 minutes after the start of the refilling. If a TPRS or CTIS and a TPMS are fitted to a vehicle, the TPRS or CTIS must remain deactivated during tests of TPMS.

N2 or N3 vehicles towing at least one O3 or O4 vehicle, and O3 and O4 vehicles, must have an interface to exchange TPMS data. The interface may be wired or wireless, provided that the TPMS equipment in the towing vehicle and in the towed vehicle(s) are compatible. Wired communication must be based on the ISO 11992 braking electric control line, or on other compatible wired specifications that fulfil the same functional requirements. For the interface of paragraph 5.6.1.1., Part A of Annex 5 sets the messages to support, and Annex 6 gives an optional test procedure. The matching warning signal must be illuminated whenever the towed vehicle TPMS provides low tyre pressure warning information or a malfunction indication through the interface. An N2 or N3 vehicle towing at least one O3 or O4 vehicle must indicate whether a warning relates to it or the towed vehicle(s).

New paragraph 5.1.6. sets TPMS reset requirements for vehicles of categories M1 up to a maximum mass of 3500 kg and N1. One requirement covers a TPMS with a reset function that does not detect a minimum pressure after reset, in case of a given warning. For this TPMS, the reset control must be designed and/or located inside the vehicle to reduce the risk of inadvertent reset by occupants or cargo. Another requirement covers a TPMS that does not detect if the pressure is above a minimum pressure after executing the reset function. Such a TPMS must include at least measures avoiding a reset if the vehicle did not become stationary after a pressure warning was issued. It must also have either measures avoiding inadvertent reset control operation or an activation by at least two deliberate actions.

The first two digits of the approval number are now 01 for the Regulation as amended by the 01 series of amendments. From the entry into force of the 01 series, no Contracting Party applying this Regulation may refuse to grant or accept 01 series approvals. From 6 July 2022 (M1 vehicle types) and 6 July 2024 (other categories), Contracting Parties are not obliged to accept approvals to the preceding series. Notwithstanding paragraph 12.4., Contracting Parties must continue to accept preceding-series approvals for vehicles/vehicle systems not affected by the 01 series changes. Contracting Parties may grant approvals to any preceding series and must continue to grant extensions of existing approvals to any preceding series. Paragraph 8.1. now refers to Schedule 1 to the Agreement (E/ECE/TRANS/505/Rev.3), and footnotes refer to document ECE/TRANS/WP.29/78/Rev.6.