To determine the max weight of a trailer that a tow vehicle can safely tow you will need the following information. The Gross Vehicle Weight (GVW) of the tow vehicle. The Gross Vehicle Weight Rating (GVWR) of the tow vehicle. The shipping / dry weight of the tow vehicle. The Gross Combined Vehicle Weight Rating of the tow vehicle. You will also need to know the GVWR of the trailer you are considering purchasing. The first step is to take the GVWR of the trailer and multiply it by 15% you will need this number later on. To determine what the vehicle can tow safely you need to do the math. The first step is to subtract the shipping/ weight of the tow vehicle from the GVWR of the tow vehicle. This gives you the cargo capacity of the tow vehicle. The cargo capacity includes a full tank of fuel @ 8.83lbs per gallon, people (150lbs per person), pets, luggage and 15% of the weight of the travel trailer that you are towing. The weight of the cargo and shipping/dry weight of the tow vehicle should never exceed the GVWR of the tow vehicle. 2nd step Take the GCVWR subtract the GVWR of the tow vehicle and that will give you the max trailer weight that the tow vehicle can safely tow and stop. That is the correct way to calculate the max trailer weight the tow vehicle can safely tow.