heavyweight wheel material for best grip

[terry]

having trouble deciding on wheel material (best grip) and centre material, the ally ones have bearings which are great but would the ally crack ? here is the page ive been looking at.

http://www.castors.org.uk/160mm-c-4.html

all ideas muchly appriciated

[adz600]

Any reply on how internal bearings hold up this is an idea I am looking at also, makes doing a 4wd machine much easier

[adz600]

these are my ideas
http://www.technicawheels.co.uk/sear...rchQuery=P1615
http://www.rosscastors.co.uk/200mm-h...er-wheels.html

[geeza]

Those are what I'm using in my new 4wd bot Adam