UN R109 — Supplement 1 to the 01 series of amendments

Paragraph 2.56. now defines “Principal grooves” as the wide tread grooves positioned in the central zone of the tyre tread. The central zone is the area that comprises 75 per cent of the tread width, measured symmetrically from the centre line. Before, principal grooves were the wide circumferential grooves positioned in the central zone of the tyre tread. For passenger and light truck (commercial) tyres, the old definition also said that these grooves have the treadwear indicators located in the base. Former paragraph 2.56.1. is now paragraph 2.56., and former paragraph 2.56. on “Tread depth” is now paragraph 2.57. Former paragraphs 2.57., 2.58. and 2.59. are now paragraphs 2.58., 2.59. and 2.60.

Paragraph 2.27. now defines “Nominal rim diameter” as a conventional number denoting the diameter of the rim on which a tyre is designed to be mounted. The diameter is expressed either by codes (numbers below 100) or in millimetres (numbers above 100) but not both. Before, paragraph 2.27. defined “Nominal rim diameter (d)” as the diameter of the rim on which a tyre is designed to be mounted. Paragraph 2.26.4. now reads “the nominal rim diameter”. Before, it gave the conventional number “d” and said that numbers for both types of measurements may be used together in the designation. Former paragraph 2.26.4.1., now 2.27.1., gives the values of the “d” symbols in millimetres when the nominal rim diameter is expressed by code.

New paragraph 2.61. defines a “Free Rolling Tyre” as “a tyre, designed for the equipment of trailer axles and axles of motor vehicles other than front axles and drive axles”. New paragraph 2.61.1. defines a “Front axle” as “any axle, forward of the mid-point of the chassis, on which the wheels are controlled by the steering system”. Paragraph 3.2.16. now reads “The inscription "FRT" in case of a Free Rolling Tyre”. Before, the paragraph itself described these tyres and used the words “front steer and drive axles”.

Paragraph 6.4.4.2. applies to retreaded tyres “produced by using either mould cure process or pre-cured tread with the same major features including tread pattern(s) as a new type of tyre approved pursuant to UN Regulation No. 117”. The condition on the new tyre type now reads “having fulfilled the requirements about minimum snow performance in severe snow conditions and/or traction tyre classification”. Before, the words “and/or traction tyre classification” were not in the paragraph.

Under paragraph 7.3., to be classified as a 'professional off-road tyre', a special use tyre must fulfil an additional requirement on its maximum speed category. For C2 tyres, the maximum speed category must be less than or equal to 160 km/h (speed category symbol Q). For C3 tyres, the maximum speed category must be less than or equal to 110 km/h (speed category symbol K). Before, paragraph 7.3. said that “a tyre” must have all of the listed characteristics. The deleted entries set a tread depth ≥ 11 mm or ≥ 16 mm and a void-to-fill ratio ≥ 35 per cent. They also set a speed category of ≤ 160 km/h or ≤ 110 km/h.

References to the provisional number “No. [XXX]” now read “No. 172”. This applies in paragraphs 2.53., 2.59., 3.4.1., 4.1.5.3.2.1. to 4.1.5.3.2.3. and 6.4.4.1. to 6.4.4.4.

Paragraph 1.1. now reads “Retreaded tyres identified by nominal speed category below eighty (80) km/h (speed category symbol "F")”. Before, it read “Retreaded tyres with a nominal speed category symbol below eighty (80) km/h”. In paragraph 2.39., the definition of “Additional service description” now says “a service description” in place of “an additional service description”. In the tables of paragraphs 4.1.5.3.2.1. to 4.1.5.3.2.3., the header of the first column now says “indices” in place of “indexes”.