When procuring a lowbed semi trailer, the most critical factor is the loading capacity, which typically ranges from 20 to 120 tons. You must verify the main beam material, ideally high-strength Q345B or T700 steel, to ensure structural integrity under heavy loads. Pay close attention to the axle brand and quantity (e.g., FUWA or BPW axles), as these determine the trailer's stability and maintenance frequency. Additionally, check the floor plate thickness (usually 3mm to 5mm checkered plate) and the ramp type, choosing between manual or hydraulic ramps based on the frequency of loading heavy machinery like excavators or bulldozers.