According to the manual any semi up to 12000 lbs fifth wheel load is correct, which means for example semitrailer,Stake and Platform, 5 ton 2 wheel, model 516 or semitrailer , animal and cargo, 6 t, 2 wheel Model SKD 1815 or model TG or 32 G or semitrailer , Gasoline tank, 6 t, 2 wheel, M30...