Detail of GB/T 2978-2024

Introduction of GB/T 2978-2024

GB/T 2978-2024 Size designation, dimensions, inflation pressure and load capacity for passenger car tyres 1 Scope This document specifies the methods for expressing size designation of passenger car tyres, the tyre size designation and corresponding dimensions, inflation pressure and load capacity as well as relevant requirements. This document is applicable to new pneumatic tyres for passenger cars. 2 Normative references The following documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. GB/T 6326 Tyre - Vocabulary GB/T 30196-2022 Self-supporting run flat tyre 3 Terms and definitions For the purposes of this document, the terms and definitions given in GB/T 6326 apply. 4 Expression methods for tyre size designation Examples of size designation of passenger car tyres Enhanced tyres shall carry the additional load identification mark, "EXTRALOAD" (or XL) or "REINFORCED (or REINF)". The radial tyre of extra-load passenger car is reinforced one, and the prefix mark "HL" shall also be added, such as HL185/70R13. For tyres which can withstand speed of 240 km/h, but not exceeding 300 km/h (W or Y speed symbols are marked on the tyres), the structural type code "R" may be replaced by "ZR". For tyres which can withstand maximum speed over 300 km/h, the structural type code "R” may be replaced by "ZR". The instructions for use in brackets are consisted of the speed symbol "Y” marked on tyres and the corresponding load index, such as 245/45ZR17(95Y). The actual load capacity and speed capacity of tyres shall be declared in technical document instructions of the tyre manufacturer. For types which meet the requirements of Class I self-supporting run flat tyre in GB/T 30196-2022, they shall be identified by marking "F" after the structural type code, such as 225/45RF 17 or 225/45ZRF 17. T-type temporary-use spare tyre shall carry the additional size designation "T" , such as T135/90D16. 5 Size designation, dimensions, inflation pressure and load capacity for tyres 5.1 The size designation and load index for passenger car tyres and corresponding load capacity, inflation pressure, measuring rim and new tyre dimension shall comply with those specified in Tables 1 to 15; the maximum service size, static load radius, rolling radius and allowable rim of the tyre should comply with those specified in Tables 1 to 15. 5.2 As for the standard and enhanced radical tyres at speed of 160 km/h or below, the correspondence of their load capability under different inflation pressure shall be as specified in Tables 16 and 17. 5.3 The correspondence between load index and load capability shall meet the requirements of Annex A. 5.4 The correspondence between speed symbols and the maximum speed shall meet the requirements of Annex B. 5.5 The pressure referenced in this document is the inflation pressure that tyres are at normal temperature and in cold state, excluding the increased pressure caused by the rising temperature during driving. In any case, the inflation pressure of T-type temporary-use spare tyres is 420kPa; the inflation pressure of radial tyres of other passenger cars shall not be greater than 350 kPa for the sake of safety. For normal conditions, the inflation pressure of high-load tyres shall not be lower than 200 kPa at any speed; the inflation pressure of other passenger car radial tyres shall not be lower than 140 kPa when the driving speed is less than or equal to 160 km/h; the inflation pressure shall not be lower than 180 kPa when the driving speed is greater than 160 km/h; for special conditions, please consult with the tyre manufacturer.

Contents of GB/T 2978-2024

Foreword i 1 Scope 2 Normative references 3 Terms and definitions 4 Expression methods for tyre size designation 5 Size designation, dimensions, inflation pressure and load capacity for tyres 6 Inflating valves Annex A (Normative) Correspondence between load index and load capability Annex B (Normative) Correspondence between speed symbol and maximum driving speed Annex C (Normative) Requirements for calculation and rounding of maximum and minimum peripheral dimensions of new tyres Table 1 Radical tyres for Series 75 passenger car Table 2 Radical tyres for Series 75 passenger car Table 3 Radical tyres for Series 70 passenger car Table 4 Radical tyres for Series 65 passenger car Table 5 Radical tyres for Series 60 passenger car Table 6 Radical tyres for Series 55 passenger car Table 7 Radical tyres for Series 50 passenger car Table 8 Radical tyres for Series 45 passenger car Table 9 Radical tyres for Series 40 passenger car Table 10 Radical tyres for Series 35 passenger car Table 11 Radical tyres for Series 30 passenger car Table 12 Radical tyres for Series 25 passenger car Table 13 Radical tyres for high-load (HLa) passenger car Table 14 T-type temporary-use spare tyres Table 15 Radical tyres a for reserved passenger cars Table 16 Correspondence between load and inflation pressure of the standard radial tyre for passenger cars Table 17 Correspondence between load and inflation pressure of enhanced radial tyres for passenger cars Table 18 Minimum inflation pressure adjustment for the radial tyre for passenger cars with speed over 160 km/h Table 19 Variation percentage of load capability of passenger car tyres at driving speed over 210 km/h Table 20 Model of inflating valves for passenger car tyres Table A.1 Correspondence between load index and load capability Table B.1 Correspondence between speed symbols and the maximum driving speed