Trailer provided with a supporting structure comprising a hitch tongue and at least one first axle, and designed to transport a cargo having a centre of gravity, this trailer being characterized in that it comprises • at least two extensometers, • links, the number of which equals the number of extensometers, each of said links comprising an adjustable gain amplification and offset shift electronic circuit and • a signal processing unit composed of a computer and also comprising an input stage provided with an analogue/digital converter and a multiplexer, said processing unit being linked to the extensometers by the respective links, and in that the extensometers are directly disposed on the structure and occupy positions whose vertical projections in a horizontal plane form a barycentric reference frame for the vertical projection, in this horizontal plane, of the centre of gravity of all of the supporting structure and the cargo, and in that the extensometers are designed to deliver raw signals (s1-s3) intended to be processed by said links to be transformed therein into output signals (S1-S3) and supplied to the processing unit, each output signal being representative of a deformation of the structure that can consist of an elastic elongation or compression in given conditions of loading or absence of loading of the trailer, and in that said processing unit is designed to receive, from the different extensometers, said output signals (S1-S3), and in that said processing unit is designed • either to calculate weighting coefficients (Ki) and associate them with each output signal (S1-S3), so as to develop a linear combination in which said weighting coefficients (Ki) are representative of the position of the extensometers in the barycentric reference frame of the corresponding extensometer; • or to calculate a common weighting coefficient K for all the extensometers and associate it with the sum of the output signals (S1-S3), so as to develop a linear combination in which this common coefficient K is representative of the position of the centre of gravity G of all of the supporting structure and of the cargo; in that said processing unit is designed to supply, from this linear combination or from several values of this linear combination, a datum (Mq) representative of the weight of the trailer and/or of the cargo. this trailer being characterized in that it comprises • at least two extensometers, • links, the number of which equals the number of extensometers, each of said links comprising an adjustable gain amplification and offset shift electronic circuit and • a signal processing unit composed of a computer and also comprising an input stage provided with an analogue/digital converter and a multiplexer, said processing unit being linked to the extensometers by the respective links, and • at least two extensometers, • links, the number of which equals the number of extensometers, each of said links comprising an adjustable gain amplification and offset shift electronic circuit and • a signal processing unit composed of a computer and also comprising an input stage provided with an analogue/digital converter and a multiplexer, said processing unit being linked to the extensometers by the respective links, and in that the extensometers are directly disposed on the structure and occupy positions whose vertical projections in a horizontal plane form a barycentric reference frame for the vertical projection, in this horizontal plane, of the centre of gravity of all of the supporting structure and the cargo, and in that the extensometers are designed to deliver raw signals (s1-s3) intended to be processed by said links to be transformed therein into output signals (S1-S3) and supplied to the processing unit, each output signal being representative of a deformation of the structure that can consist of an elastic elongation or compression in given conditions of loading or absence of loading of the trailer, and in that said processing unit is designed to receive, from the different extensometers, said output signals (S1-S3), and in that said processing unit is designed • either to calculate weighting coefficients (Ki) and associate them with each output signal (S1-S3), so as to develop a linear combination in which said weighting coefficients (Ki) are representative of the position of the extensometers in the barycentric reference frame of the corresponding extensometer; • or to calculate a common weighting coefficient K for all the extensometers and associate it with the sum of the output signals (S1-S3), so as to develop a linear combination in which this common coefficient K is representative of the position of the centre of gravity G of all of the supporting structure and of the cargo; • either to calculate weighting coefficients (Ki) and associate them with each output signal (S1-S3), so as to develop a linear combination in which said weighting coefficients (Ki) are representative of the position of the extensometers in the barycentric reference frame of the corresponding extensometer; • or to calculate a common weighting coefficient K for all the extensometers and associate it with the sum of the output signals (S1-S3), so as to develop a linear combination in which this common coefficient K is representative of the position of the centre of gravity G of all of the supporting structure and of the cargo; in that said processing unit is designed to supply, from this linear combination or from several values of this linear combination, a datum (Mq) representative of the weight of the trailer and/or of the cargo.