fmcsa rules concerning trailer modifications?

I have a front tilt deck flatbed 4 car hauler. I want to add a deck that raises and lowers using hydraulics. It entails cutting and welding and thus modifying the trailer from its original design. I plan to have a certified welder do all the work. But, I can't seem to find any rules governing the modification of a commercial car hauling trailer. Does anybody out there have any LEGAL referances concerning this subject that I can look up for myself? I'd hate to pay all that money out to have it built then only to find out that it was illegal or something, then have my trailer shut down by dps.

riley in San Antonio, Texas said: I have a front tilt deck flatbed 4 car hauler. I want to add a deck that raises and lowers using hydraulics. It entails cutting and welding and thus modifying the trailer from its original design. I plan to have a certified welder do all the work. But, I can't seem to find any rules governing the modification of a commercial car hauling trailer. Does anybody out there have any LEGAL referances concerning this subject that I can look up for myself? I'd hate to pay all that money out to have it built then only to find out that it was illegal or something, then have my trailer shut down by dps.

the only regulations that i know of governing trailers is length, width,height and axle spreads and limitations. when it comes to trailers and modifications i dont believe there are any, but it must still be able to pass a safety inspection. typically if there is no cracked welds, frame and cross members arent rusted thru and they gvw and the axles are rated to carry the weight u should be fine. when in doubt go to a scale house and ask them or call them up. typically dot enforcement know less about trailers than the ones driving them. they usually go by the book and the book does not encompass modifications. book goes by width, height, length and gross vehicle weight according to the axle weight. they also go by an axle length and spread but i never understood it. if the modification is clean and neat and not all chopped up i dont think the dot enforcement is even going to know! hope this was helpful