BS AU 50-4.4.1:1991 download free.Tyres and wheels Part 4. Rim profiles and dimensions Section 4. Agricultural tractor and machine rims Subsection 4.1 Specification for existing (inch) series rims.
1 Scope and field of application
This part of ISO 4251 sets out rim dimensions and rim coordinations for existing series of tyres for agricultural tractors and machines.
Tyre designation and dimensions, load ratings. and tyre classification and nomenclature are given in ISO 4251/1, ISO 4251/2 and ISO 4251/4 respectively.
2 Rim diameters
Nominal diameter size codes and specified diameters of rims are given in table 1 and shown in figure 1.
The specified diameters. D, are derived from the nominal diameter size codes, DR. as foJlows:
a) for DR = 15.3. D = 25,4 x 15,288 = 388,3 mm; for all other rims with
DR c 16,D= 25,4(DR — 003125)mm;
bi for DR = 16.1, D = 25,4 x 16,043 75 = 407,5 mm;
c) for DR > 16.1, D = 25,4 (DR + 0,1875) mm.
For tyre design purposes only, a tolerance of ± 0,4 mm on the specified diameter, D. may be applied.
For rim diameter measurements, see the annex.
A tolerance of ± 1.2 mm on nni circumference is permitted.
3 Rim contours and valve holes
3.1 Drop centre W and DW rims
Dimensions and tolerances of drop centre W and DW rims are given in table 2 and shown in figure 2.
The location and dimensions of valve holes are shown in figure 2.
The valve hole shall have a diameter of 15.7 ‘ mm and may be on either side of the rim.
The valve seat angle is 30 ± 50 nominal. To provide for valve to vehide dearance, optional valve seat angles of 15° minimum to 50° maximum are permissible. For any angle selected for a given rim, the tolerance is ± 5°.
3.2 Other drop centre rims
Dimensions and tolerances of other drop centre rims are given in table 3 and shown in figure 3. (Fgure 4 gives dimensions and tolerances for a semi-drop centre rim 16.1 — 11 SDC.)
The normal location of valve holes in C, D, E, F and LB rims is shown in figure 3. The va)ve hole may be on either side of the rim well.
The valve hole diameter shall be:
a) 15,7 mm for rims of nominal diameter size code 15 and above;
b) 11,3 g4 mm for rims of nominal diameter size code 14 and below.
An optional location of valve holes in C, D, E, and F rims of diameter size code 15 and above (valve hole diameter
15,7 ‘ mm is shown in figure 5.
Thelocation of valve holes in rimsW 10 Land 16.1 x W 11 C
and an optonal location of valve holes in the corner of the well
of LB rims is shown in figure 6.
To provide for valve to vehicle clearance in LB rims, optional valve seat angles of 15° minimum to 50° maximum are permissible. For any angle selected for a given rim, the tolerance is
± 5°.
3.3 Divided rims
Dimensions and tolerances of divided rims are given in table 4 and shown in figure 7.
The location of valve holes is shown in figure 7. The valve hole diameter shall be:
a) 15,7 + 0.4 mm for rims of nominal diameter size code 15
and above;
b) 11,3 ‘ mm for rims of nominal diameter size code 14 and below.
4 Rim knurling
Transverse knurling is optional on W and DW rims as shown in figure 2 and according to table 2. with the following specifica tions:
a) knurling shall start 9,5 ± 0,8 mm from the flange and shall be 1.6 mm minimum from the bead seat radius;
b) the depth of knurling shall be 0.4 to 0,8 mm;
C) the pitch of knurling shah be 1,6 to 3,2 mm.
5 Rim coordinations
In addition to the measurement rim width given in ISO 4251/1,
the preferred rims and the permitted rims are specified:
— in table 5 for agricultural drive wheels, tractor tyres;
— in table 6 for agricultural steering wheels, tractor tyres;
— in table 7 for agricultural implement tyres with normal section height;
— in table 8 for agricultural implement tyres with low section height.
NOTE — Rim coordinations for garden tractor tyres are under study.