The load capacity given one based on maximum value under ideal conditions of use with progressive speed(max 4km/h) on flat surfaces. The minimum load capacity per castor is calculated as the sum of the weight of the carrier plus the maximum added load divided by 3.

Load Capacity = Weight of Carrier + Additional Load
                                                3

However, if the castors are to be subjected to unusual shock or impact or uneven floors, then the next greater castor capacity is advised.

Wheel Material:
For applications include exposure to oils, grease, acid solution and other unusual environmental conditions.

Wheel Hardness:
Hard tread wheels normally require less starting force, advantages are higher load capacity. Soft wheels roll easier over obstruction, provide better floor protection, shock absorption and traction

Wheel Diameter:
Large wheel roll easier, is more maneuverable, can overcome obstruction and floor ruts easier than smaller diameter wheel

Plate fitting:
Plate type fitting normally mounted on flat surface.

Bolt Hole Fitting:
Hollow attachment allowing fitting by bolt and nut.

Stem fitting:
Solid or threaded for fitting into tubes.

Ball Bearing:
Low noise, meets highest demands of load capacity, especially suitable for heavy duty castors.

Roller Bearing:
Robust and maintenance free, rolling resistance low even with heaviest load.

Plain Bearing:
Value for money, suitable for outdoor usage.

Flange Bearing:
Light running bearing, low noise especially suitable for apparatus castors.

TYRE MATERIALS	NATURAL RUBBER	NATURAL SOFT RUBBER	PU	PLASTIC PP/NYLON
Hardness Shore A	80	70	90	>95
Elasticity	moderate	super	good	fair
Compression Strain	moderate	moderate	super	fair
Wear Resistance	moderate	good	super	good
Weather Resistance	moderate	moderate	super	good
Oil Resistance	fair	fair	super	super
Gasoline Resistance	no good	no good	good	good
Chemical Resistance	no good	no good	good	good
Starting Resistance	moderate	moderate	super	good