Weight of the Trailer
Fifth wheels and travel trailers carry their weight differently. The weight of a fifth wheel is largely transferred to the bed of the large tow vehicle (truck) that is pulling it. The weight of a travel trailer rests on its tongue and is transferred to the hitch of the tow vehicle. It is important to determine how much of your RV's weight will be transferred to your tow vehicle. Many RVs will list a hitch weight, but this is only a dry hitch weight and does not include anything you add into the trailer (cargo). So it's best to calculate it based on the max weight the trailer can handle so you don't have to worry about how much cargo you bring along on your getaways. Either way, you need to find the Gross Vehicle Weight Rating (GVWR) of the trailer to begin. This will be found on a sticker near the door (or in the specs). This is the full amount of weight the trailer can handle including itself and any cargo you put in it. 5th Wheels A fifth wheel hitches up over the rear axle of the truck on a hitch put into the bed. The part of the hitch it's putting its weight on is called the pin, so the weight you need to calculate here is the pin weight. Fifth wheels put between 20-25 percent of their weight on the pin, so in order to see how much will transfer to your vehicle, you simply multiply the GVWR by the percentage (use 25 percent just to be safe). Travel Trailers Sometimes referred to as bumper pull trailers, travel trailers rest on the hitch ball and carry more of their own weight on their axles. The weight put on the ball is called tongue weight and is usually between 10-15 percent of the trailer's weight. Just as we did with the fifth wheel, multiply the GVWR by the larger percentage (15 percent). Now that you know how to calculate the amount of weight that will be put on your tow vehicle, you need to figure out if your tow vehicle can handle that much weight. It may be tempting to go by the max towing capacity here, but there are some factors not included in this number, such as cargo weight. You now need to figure out how to calculate your payload.
Payload of the Tow Vehicle
The payload is going to be what the tow vehicle can handle on the chassis after the weight of itself, occupants, and any cargo stored inside it are added together. You need to determine the GVWR of your tow vehicle. Look in the door jams of the vehicle to find this information. If the weight sticker does not show GVWR, look for the Tire and Loading Information, which will give you an amount you cannot exceed with occupants and cargo. If you have the GVWR, this will be easy. This is the max amount of weight it can handle between itself, occupants, cargo, and anything it's towing. The first thing you need to figure out is how much your cargo weighs altogether (passengers, pets, food, clothing, etc.). The best way to do this is to pack up everything and everyone into your vehicle and get it weighed at a weigh station and or a truck stop. If weighing your load isn't an option, or if you only have the information from the Tire and Loading sticker, you will want to figure out all the weights separately. Start with your passengers and any other things you will want to have in your vehicle. This includes luggage, tools, food, etc. Next you need to research the curb weight of your vehicle. You can usually find this weight on the manufacturer's website for your type of vehicle. Once you have this number, you can calculate your total weight as well as what's left over.
Now that you have all these numbers, you need to know what to do with them. We will show an example using a Chevy Silverado 1500 and Eagle RVs. We have a list that looks like this: Tow Vehicle: GVWR: 6,700 lbs. Total weight from scale: 4,927 lbs. Curb Weight: 4,517 lbs. Weight of passengers & stuff: 410 lbs. Occupant & Cargo Max: 2,183 lbs. RVs: 314BHDS Travel Trailer GVWR: 9,975 lbs. and 291RSTS 5th Wheel GVWR: 12,000 lbs. Let's put our numbers to work! First let's see how much weight our RVs are going to put on our Silverado 1500. Remember that we use 15 percent of the travel trailer and 25 percent of the 5th wheel: Travel Trailer: 9,975 x .15 = 1,496.25 lbs. Tongue Weight 5th Wheel: 12,000 x .25 = 3,000 lbs. Pin Weight Next let's see if our truck can handle these weights. We'll use the GVWR method first and then the method with just the max passengers and cargo. Let's subtract the number we got from the scale from the GVWR and see if we have enough left over for the trailers: 6,700 – 4,927 = 1,773 lbs. Payload If you have the GVWR and can't get it weighed, simply add the weights off all your items and passengers to the curb weight and this will get you the same number that you would get from the scale. If we're working with the max passengers & cargo, it will look a little more like this: 2,183 - 410 = 1,773 lbs. Payload We get the same answer, so we can assume that we're accurate. The 5th wheel is going to put 3,000 lbs. on our truck, which is 1,227 lbs. over our weight limit, so we cannot pull this one. The travel trailer, however, is only putting 1,496.25 lbs. on the hitch, which is 276.75 lbs. under our payload, so we can support it on the chassis. Now we just need to make sure we're not going to burn out our engine trying to move them! Our Gross Combined Weight Rating (GCWR) is the total amount of weight the engine can handle between both vehicles. We simply need to add the GVWR of both the tow vehicle and the trailer and ensure we're not going over our GCWR. 6,700 + 9,975 = 16,675 lbs. 6,700 + 12,000 = 18,700 lbs. Since our GCWR on the Silverado 1500 is 17,500, our engine can handle the travel trailer just fine. However the 5th wheel is too heavy and our truck's engine can't tow it safely. So let's say we want to keep shopping around for a "just right" travel trailer. What is the easiest way to do this without having to weigh every single RV we're interested in?
The Biggest Trailer We Can Pull
Now that you have all the calculations for your truck, you can simply figure out how heavy of a trailer you can handle by switching around some numbers. We just need to know what the percentage of the highest weight we can tow would be. You simply need to divide by the percentage based on your payload. Here's how it works: Travel Trailer: 1,733/.15 = 11,553 lbs. 5th Wheel: 1,733/.25 = 6,935 lbs. Now we need to check our GCWR, so we simply subtract the GVWR of the tow vehicle from the GCWR: 17,500 – 6,700 = 10,800 lbs. This information allows us to easily search RVs based on the weight of the trailer we can pull. This should save you a lot of time and frustration! Now that you have exercised your old math skills, you can confidently start shopping for your new RV! As you look around, keep in mind that families change and grow. A family of three can quickly grow into a family of five, and small toddlers seem to turn into teenagers overnight. To ensure that you won't outgrow your new RV in just a few years, choose ones that have room to grow!