tyres
Tyres
Solid tyres for vintage vehicles
In the UK press-fit solid band tyres were produced for nominal metric wheel diameters.
According to period drawing the tolerance on a 720mm (nominal) wheel was 2262mm to 2263mm circumference.
Data from period Dunlop literature
Nominal Diameter
670
720
741
771
850
881
Minimum circumference
2104.9
2262.0
2327.9
2422.2
2670.3
2767
Maximum circumference
2105.9
2263.0
2328.9
2423.2
2671.3
2768
"Pressure for Fitting" (Dunlop literature)
Section under (mm)
75
85-90
100-110
120-130
140
160
Minimum pressure (tons)
7
10
12.5
15
17.5
20
Maximum pressure (tons)
14
20
25
30
35
40
In order for the bands to be reusable (re-rubbered) the bands must stay within their elastic limit. The yield stess of mild steel can be taken to be 200 MPa; Young's modulus can be taken as 200 GPa giving a yield strain of 0.001 (200MPa/200GPa) or an extension of 0.1%. This equates to a maximum extension of around 2.25 mm (2260 circumference*0.001).
If a band is made less than 2259.75mm circumference then the band will be stretched when fitted and when removed relax to 2.25mm less than the wheel circumference.
A lower limit of 2260.75mm would ensure the bands do not plastically deform even it the wheel is on the upper 2263mm limit of circumference.
Engineers edge: 0.6 diameter = 15tons (1.88circum). 1.2 diameter = 30tons (3.8 circum)
Using P =(AaF)/2
P=Pressure in tons, A = Area of surface in contact, a = total allowance (shaft diameter-bore diameter), F = pressure factor.
Overall diameter (various sources)
Sorry, this layout has been messed up by Google sites dropping support for tables.
Diameter
Section
65
75
85
90
100
110
120
130
140
160
180
670
810
820
825
830
860
842
720
850
860
863
873
880
866
912
892
741
850
870
771
920
943
850
1000
1022
881
1030
1050
1050
1050
1060
Section
65
75
85
90
100
110
120
130
140
160
180
670
810
820
825
830
860
842
720
850
860
863
873
880
866
912
892
741
850
870
771
920
943
850
1000
1022
881
1030
1050
1050
1050
1060