I have 7.5 tons and can drive with my old FS III up to 12 tons. Therefore, the GG of a Tandemach trailer should not exceed 4.5 tons in order to be able to drive up to 12 tons toll-free. However, Tandemach trailers with GG of 5 tons are offered with the indication that this can be driven toll-free. 7.5 and 5 tons results according to Adam Riese but 12.5 tons, so I am about the 12 tons. Can someone tell me how it actually behaves.