Wow.... have just come back to this thread and its grown!
Thanks for all the advice guys... some of the replies have been a breath of fresh air
personally i think the straps themselves are definately strong enough, after all they hold cars on the backs of lorries etc..
BUT what do you secure them to? There's the problem I think.
I agree with this... and the comment about the Eden project delivery... I see cars on the back of low loaders all the time, and if it was so insecure, then I'm sure the Police would be on to it.
I think the best place to secure them would be the manufacturers load points.... they haven't been added in after, and I assume they're secured to the chassis. If a commercial vehicle payload is rated at 500kg, or 1000kg, or whatever, then I can imagine, in our H+S mad society, the manufacturer would be required to provide a safe means of lashing down the entire payload?