BS ISO 7867-2:2018 pdf download – Metric series for agricultural, forestry machines and construction tyres Part 2: Load ratings for agricultural tyres
5 Tyre load ratings
5.1 Basic tyre load
Basic tyre load is the tyre load-carrying capacity indicated by the tyre’s load index at the reference speed indicated by the tyre’s speed symbol in the principal service description.
When used as duals, tyre loads shall be reduced to 88 % of the basic tyre load.
When used as triples, tyre loads shall be reduced to 82 % of the basic tyre load.
For basic tyre loads and reference inflation pressures of some existing tyre sizes, see:
— standard tractor drive wheel radial tyres, given in Table A.1;
— standard tractor drive wheel diagonal tyres, given in Table A.2;
— IF tractor drive wheel radial tyres, given in Table A.3;
— implement tyres with speed symbol A6 or A8 in Table B.1;
— implement tyres for mixed applications with speed symbol D in Table B.2.
5.2 Tyre applications at service speeds other than the reference speed
5.2.1 General
The rim/wheel manufacturer shall be consulted for confirmation of the suitability of the rim/wheel for the intended service.
5.2.2 Tractor drive wheel tyres
5.2.2.1 General
For applications with low torque, including road transport, the load/speed relationship is given in Table 1.
The tyre manufacturer concerned shall be consulted for the actual pressure to be used when applying the load/speed relationship given in Table 1, especially for service speeds 10 km/h and below.
5.2.2.2 Standard metric drive wheel tyre for field application with high and sustained torque For this application, the values shown for service speed 30 km/h in Table 1 apply.
5.2.2.3 Standard metric drive wheel tyre application on combine harvesters
5.2.2.3.1 General
On combine harvesters in cyclic loading application, except hillside combines, load and inflation pressure increases are shown in Table 2. This load increase shall include all possible field and user modifications that increase the vehicle mass and shall apply only to load increases which occur during the harvesting process. For hill-side operations over 11° (20 %) slope, only the basic tyre loads are permitted.
5.2.2.2 Standard metric drive wheel tyre for field application with high and sustained torque For this application, the values shown for service speed 30 km/h in Table 1 apply.
5.2.2.3 Standard metric drive wheel tyre application on combine harvesters
5.2.2.3.1 General
On combine harvesters in cyclic loading application, except hillside combines, load and inflation pressure increases are shown in Table 2. This load increase shall include all possible field and user modifications that increase the vehicle mass and shall apply only to load increases which occur during the harvesting process. For hill-side operations over 11° (20 %) slope, only the basic tyre loads are permitted.
5.2.2.5 IF and VF metric drive wheel tyres in cyclic loading applications
No increase in load or inflation pressure is permitted when an “IF” or “VF” tyre is used in combine service.
5.2.2.5.1 IF-CFO drive wheel tyre application in cyclic loading applications
For tyres marked with the suffix CFO (cyclic field operations), loads and pressures in Table 5 apply.
5.2.2.6 IF and VF metric drive wheel tyre application on tractors with front end loader
In cyclic service with a front end loader at speeds up to 10 km/h, a load up to 140 % of the basic tyre loads is permitted with an inflation pressure increase of 80 kPa. Cyclic service is defined as an intermittent load transport over a maximum distance of 1 km with minimum torque. In unloaded mode, the tyre load shall not exceed the basic load capacity.
5.2.3 Tractor steering wheel tyres
5.2.3.1 General
For applications at service speeds other than that indicated by the tyre service description, the load/speed relationship is given in Table 6.
The tyre manufacturer concerned shall be consulted for the actual pressure to be used when applying the load/speed relationship given in Table 6.BS ISO 7867-2 pdf download.