well I do know but take 0,5 x 25 ton * ( m/s )^2 = at 30 mph it is 0,5 * 25.000 * (48000m/3600 sec)^2 = 0,5 * 25000* (13,3)^2 = 2200 ton of kinetic energy is released if stopped at once.
When you strap it real tied, with no slack at all on the chains it may hold, but if there is a little speed build up any chain will snap. I suggest you take some serious chains, not one that holds the dog.
Peter
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