Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 2979-2008 Size designation, dimensions, inflation pressure and load capacity for agricultural tyres. The following technical changes have been made with respect to GB/T 2979-2008:
——The inflation pressure and load capacity of British agricultural radial tires have been adjusted and the ply rating changed to load index (see Table 2);
——The size designation for metric agricultural radial tyres have been added (see Table 3);
——Some size designations have been added (see Table 1 ~ Table 15);
——All-terrain vehicle tyres have been removed (Table 15 of Edition 2008);
This standard is redrafted by reference to but is not equivalent to ISO 4251-1:2017 Tyres (ply rating marked series) and rims for agricultural tractors and machines — Part 1: Tyre designation and dimensions, and approved rim contours, ISO 4251-2:2017 Tyres (ply rating marked series) and rims for agricultural tractors and machines — Part 2: Tyre load ratings, ISO 4251-4:2010 Tyres (ply rating marked series) and rims for agricultural tractors and machines — Part 4: Tyre classification and nomenclature and ISO 4251-5:1992 Tyres (ply rating marked series) and rims for agricultural tractors and machines — Part 5: Logging and forestry service tyres.
This standard was proposed by the China Petroleum and Chemical Industry Association.
This standard is under the jurisdiction of SAC/TC 19 National Technical Committee on Tyres and Rims of Standardization Administration of China.
The previous editions of the standard replaced by this standard are as follows:
——GB/T 2979-1982, GB/T 2979-1991, GB/T 2979-1999, GB/T 2979-2008.
Size designation, dimensions, inflation pressure and load capacity for agricultural tyres
1 Scope
This standard specifies the terms and definitions for
agriculture tyres, the methods for expressing tyre size designation, tyre size designation, dimensions, inflation pressure, load capacity, tire pattern and valve.
This standard is applicable to new pneumatic agriculture tyres.
2 Normative references
The following documents are normatively referenced in this document and are indispensable for its application. For dated reference, only the edition cited applies. For undated references, the latest edition of the referenced documents (including any amendments) applies.
GB/T 6326 Tyre terms and definitions
3 Terms and definitions
For the purposes of this standard, the terms and definitions given in GB/T 6326 apply.
4 The methods for expressing the size designation for tyres
Agriculture tyres are defined and expressed in terms of tyre size designation and other markings.
Example:
Example of size designation for agricultural tyre.
5 Size designation, dimensions, inflation pressure and load capacity for tyres
5.1 Size designation, ply rating for tyres and the corresponding load capacity and inflation pressure, measuring rim, new tyre dimensions, the maximum tyre dimensions in service, model of valve and permitted rim shall be in accordance with those specified in Tables 1 ~ 16.
5.2 The following requirements shall apply to calculation of the maximum and minimum section width of new tyres:
Minimum total width of the new tyre = designed section width × a;
Tyres other than paddy bias-ply tyres for agricultural tractor drive wheels a=1.06
Paddy bias-ply tyres for agricultural tractor drive wheels a=1.12
Minimum total width of the new tyre = designed section width × 0.96
5.3 The following requirements shall apply to calculation of the maximum and minimum outer diameter of new tyres:
Maximum new tyre outer diameter = 2 × designed section height × b + nominal rim diameter;
——Radial tyres for agricultural tractor drive wheels b=1.04
——Bias-ply tyres for forestry machinery and agricultural tractor drive wheels b=1.05
——Paddy bias-ply tyres for agricultural implements and agricultural tractor drive wheels b=1.06
——High-throughput tyres, horticultural tractors and paddy bias-ply tyres for agricultural tractor drive wheels b=1.08
b) Minimal new tyre outer diameter = 2 × designed section height × 0.96 + nominal rim diameter;
5.4 Air weight specified in Tables 1 ~ 16 is measured when the tyre is at ambient temperature, without including increased air pressure due to vehicle movement. The inflation pressure specified in Table 1 ~ Table 16 is the minimum pressure under the corresponding load speed. If the driving speed changes, adjustment shall be conducted according to the regulations in the tyre size designation tables.
5.5 The load capacity specified in Tables 1 ~ Table 16 is the maximum load under the corresponding service conditions. In actual use, adjustment may be conducted according to the corresponding relationship between load capacity and speed given in the tables.
6 Tread pattern
6.1 Categories of tread pattern
The classification of agricultural tyre tread patterns shall comply with the regulations of Table A.
6.2 Design of tread pattern depth
See Annex B for the design of tread pattern depth
7 Tyre valve
The model of tyre valves shall meet the requirements of Tables 1 ~ 16, and shall be settled through negotiation between the user and the manufacturer if other models are used.
Foreword iii
1 Scope
2 Normative references
3 Terms and definitions
4 The methods for expressing the size designation for tyres
5 Size designation, dimensions, inflation pressure and load capacity for tyres
6 Tread pattern
7 Tyre valve
Annex A (Normative) Categories of agricultural tyre tread patterns
Annex B (Informative) Depth of agricultural tyre design tread
