Bhg, The comp I used to work for tried to run older HGV Trailers with a third Axle, the weight went up from 20tonnes to 24, I was coming back from Sheffield over to Manchester, I felt a crack & the whole lot Jerked, the trailer was loaded with Bricks from Lincoln, the Trailer's Neck cracke at the "Swan's" neck just near the Fifth wheel, they had to weld and Strengthen the Swan Neck, the trailers was never made for that weight & the whole fleet of Trailers had to be replaced.