information | Conversion Charts

Conversion Charts

When a country converts to metric it does not simply change the dimensions from inches to millimetres, but takes the chance to make the range offered more rational in both terms of international usage and what already exists. So some things change a lot, while others do not change much.

Tubing has remained in inch sizes, but is described in metrics. Tubing is specified by its outside diameter and wall thickness. The main sizes used for the legs of trolleys to which castors are fitted are shown in this table.

Conversions Preferred sizes for
New name
OD x
Old name
OD x wall
Internal diameter Used on Series Tubing Wire Black round Bright round
12.7x0.9 1/2"x20G 10.9 (7/16") L - 4 - 4
16x1.2 5/8"x18G 13.6 (1/2") L - 6.3(5/8") - 6
19x1.2 3/4"x18G 16.6 (5/8") L - 8 - 8
22.2x1.6 7/8"x16G 19.0 (3/4") K,M - 10 10 10
22.2x1.4 7/8"x17G 19.4 (3/4") K,M 12.7 (1/2") 12.5 12 12
22.2x1.2 7/8"x18G 19.8 (3/4") K,M 16 (5/8") 16 16 16
25.4x1.6 1"x16G 22.2 (7/8") K,M 19 (3/4") 20 20 20
25.4x1.4 1"x17G 22.6 (7/8") K,M 25.4 (1") 25 - 25
25.4x1.2 1"x18G 23.0 (15/16") K,M

Note: When fitting wheels to axles you need to be careful as to whether the axles are made from wire or black bar or bright round, as this might affect the actual size and thus the neatness of fit. You will also need to be careful if the article has been powder coated as this could add to the diameter and make a fit too tight.

In many wheels we can offer special 'off-standard' bushings at little extra cost. Check your needs carefully, then talk to a Fallshaw representative.

31.8x1.2 11/4"x17G 29.0 (13/16") M,J
31.8x1.2 11/4"x18G 29.4 (13/16") M,J
Conversion Charts
Length Tolerances Temperature Mass (load) Speed Pressure
mm ins mm ins °C °F kg lbs km/hr mph kpa psi
3.18 1/8" 0.01 0.0004 -73 -100 40 88        
4.76 3/16" 0.05 0.0002
(2 thou)
-50 -58 80 176 6 3.75    
6.35 1/4" -20 -4 100 220 10 6.21 210 30
7.94 5/16" 0.10 0.004
(4 thou)
0 32 200 441 16 9.94 250 36
9.53 3/8" 60 140 400 882 50 31.07 350 50
11.11 7/16" 0.50 0.020
(20 thou)
100 212 680 1500    
12.70 1/2" 120 248 1000 2205
15.88 5/8" 0.76 0.030 150 302  
19.05 3/4" 1.00 0.039 200 392
25.40 1" 2.00 0.079 250 482