Specifics? Tandem, tridem, steel, aluminum, 45', 48', 53'? Generally, you're looking at 15,000 - 19,000 lbs, depending on specifics.
All states require flatbed trucks to have a headache rack. It can either be mounted as part of the trailer, or mounted on the tractor.
the 40ft flatbed semitrailer length 12.5m / 2.5m width and we are makeing this dimentions
If you don't have a headboard mounted on the trailer itself, then yes, you do.
Yes, and for any open deck trailer, if the trailer doesn't already have its own headboard.
There is no minimum weight.
14,000 lbs
Most trailers are semi trailers. You're probably asking the difference between a semi trailer and a full trailer. A semi trailer is not wholly self supporting, and weight is distributed both the trailer axles, and to the tow vehicle. A full trailer supports its own weight fully.
69,500 pounds
truck and trailer 35000 pounds.
Well, that all depends on the trailer. With a Freightliner and an aluminum 48' flatbed trailer, I've always been able to haul in the vicinity of 48,000 lbs. on the trailer.
The weight capacity for semi trailer is 80,000 LBS. That is calculating with two or more consecutive axles to the nearest 500 LBS.
You have to put your weight evenly between your trailer axles and your trucks rear axles. You have to know the weight limit of your truck and trailer, it should say in the owner's manual or you can read the weight limit on the tires. The majority of the weight should be on the trailer because if you put most of the weight on the truck the trailer will begin to fishtail. If it is a flatbed trailer and you look along the side you will see that it bows up, you should never load it to were it bows down because it is probably overloaded at that point. Also you should read the owner's manual to learn how to move the axles on the trailer.