When you say tonnes, am I correct in assuming you mean a metric ton which is 2200 poundsIJ Does the 50 tonne weight limit include the weight of the truck or just the grain it is haulingIJ In the US the gross weight of a semi-truck with two axles on the tractor and two axles on the trailer is 80,000 pounds. In western Kentucky, where I live, the coal trucks can legally run at 120,000 pounds gross weight and in eastern Kentucky they can legally run 160,000 pounds gross, but I am not sure if they have to have extra axles.