I have a question about how to calculate what size of steel tubing to use in building a boom for a wrecker. Tentatively the compressed length will be 12, and extended I would like to be 28' as this will be a 3 stage boom. I would like to have a safe working load limit of 5Ton at full extension. I need to know tube diameter and wall thickness to attain this. If further specifications are needed, just let me know.