yep they do have a few more, but im stuck as to what material will give best grip,

polyurethane, elastic rubber etc,

also im thinking of getting the wheels with 20mm bearings in so its less work

they mostly have aluminium hubs and im worried they will crack as they look cast ?

mind you though they are rated up to 800kgs sometimes so prob ok

this one looks good but not too cheep up too the job but not sure about grip

there is some more on the page below aswell.

http://www.rosscastors.co.uk/160mm-heav ... rings.html