[size=6][sup][quote name='Ed_S' timestamp='1322739228' post='1455059']
Machine Mart do a decent range of wheels, as well as ready-made dolly boards. Worth a look if you want to actually walk into a shop and handle stuff to get a feel for what's going to work best, rather than ordering online. They do some that whilst small and solid, are a bit more of a rubbery compound and work better when you hit rough and uneven surfaces.
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[sup]I would suggest a dolly board as the cheapest, easiest route - a decent flat length of 1" thick marine ply with a 4" rubber-tyred castors near each corner.[/sup][/size]