It is far better to choose a wheel of the correct diameter to suit the application, rather than choosing the smallest wheel with the highest load capacity.
The following is a guideline which should be used to choose the correct wheel in order for the finished object to be easily pushed.
50mm castors – light loads, mainly static use.
75mm castors – light loading, generally less than 80 kgs.
100mm castors – for loads up to 310 kgs.
125mm castors – for loads up to 500 kgs.
150/160 castors – for loads up to 800 kgs.
200mm castors – for loads over 800 kgs.