Usually 20 to 23 tons, depending on what the tare weight of the combination is. Although I do believe wood chips are sold by the cubic yard, rather than by the ton.
The weight that can be carried in a semi trailer legally varies. It depends on how much the tractor pulling the trailer weighs. The maximum weight of the total unit, truck and trailer is limited at...
It depends on where you're at. In North America, they'll typically range from 27 to 53 feet in length, with the 53' dry and refrigerated vans and 48 ft. flatbeds and tankers being the most common.