GVW (Gross Vehicle Weight) and GW (Gross Weight) are interchangeable terms meaning the actual weight of the vehicle (trailer) and its complete load. This weight can be determined by loading the horses, tack, feed, and hay etc. into the fully equipped trailer (mats, spare tire, etc.) and taking it to a truck scale to have it weighed. Most gravel yards or truck stops have truck scales. GVWR (Gross Vehicle Weigh Rating) is the value specified by the manufacturer as the recommended maximum loaded weight of a single vehicle. (This is what we put as 9900 lbs) For a trailer this value is determined by the axle capacity and the coupler capacity. For example, a trailer will be rated at 5000 lbs. GVWR by the manufacturer if it has two 2500 lb. axles and a 2 inch ball coupler that is rated 5000 lbs. Loading the trailer to excess of the GVWR is not only unsafe, but is illegal.