Hooking up a caravan gives your vehicle a lot more to control as you drive. The towing vehicle controls the caravan with its weight. A car or other tow vehicle that weighs too little can result in the caravan pulling the car around when the wind blows or swaying dangerously. A trailer that is too heavy can also move around on the road so much that it pulls the tow vehicle off the road. Safe towing means determining the right towing weight for your vehicles.
Find the tow-weight rating of the tow vehicle. This is often printed on a manufacturer's sticker on the door jam or sometimes listed in the owner's manual. You can also check with the manufacturer or a dealer. You want to find the Gross Combination Weight Rating. This is often abbreviated to GCWR.
Find the weight of the unloaded car. This should also be listed on the door jam or in the owners manual. This is called the Gross Vehicle Weight, abbreviated to GVW.
Adjust the GVW by adding in the weight of any passengers and cargo you plan to carry. For example, if you're taking three people and yourself on the trip, you should add the weight of those four people and all their equipment. The most accurate way to do this is to load the car up (without the trailer) and get it weighed on a scale. If there is no scale available, you can add up the weight of each individual person and the weight of the luggage and add it to the GVW to get the total adjusted GVW.
Calculate the maximum trailer weight by subtracting the GVW from the GCWR (GCWR - GVW = Maximum Trailer Weight). This gives you the maximum weight of the trailer the tow vehicle can handle. Bear in mind that this weight is the total weight of the loaded trailer. If you plan on carrying a lot of gear in the trailer, make sure you factor that into the trailer weight.
Be cautious and err of the high side while calculating the weight of your vehicle, in case you add someone or something extra at the last minute.
Leave a safety margin of about 20 per cent so that you don't accidentally exceed the safe weight for your vehicle. The weight a vehicle can tow has nothing to do with the power it produces.