How Big Of A Trailer Can My Truck Tow?
Towing capacity and payload are hot topics when it comes to trucks and it can be hard to decipher just how much weight your truck or vehicle can safely tow.
Salespeople and Manufacturers naturally want you to think their trucks are tough as nails and can easily tow space shuttles, but the truth is your truck probably can’t safely tow as much as you’re being told.
In this article, I’m going to explain what everything you need to know means and how it’s going to help you when calculating if your truck can tow a certain travel trailer or 5th-wheel.
Hopefully, it will help you figure out what size of trailer you can get or how much gear you can bring with you before going over the limit.
The Info You Will Need To Calculate Towing Capacity
The first thing you are going to have to do is find the right information about your truck and the trailer you own or the one you want to buy.
Most of the information you will need about your truck or towing vehicle can be found on the sticker inside the driver’s side door jam.
Newer vehicles have more towing information on the sticker and it might be the only place you need to look. O
lder vehicles can be a little more tricky. My 2004 Dodge Ram 2500 had very little information on the sticker and Dodge no longer posted towing information on their website.
I had to do quite a bit of searching online before I finally found all the information I needed.
Words You Will Need To Know For Your Truck
How much a truck weighs with no passengers, cargo, or load. Basically what your empty truck weighs just sitting there.
Curb weight does include everything necessary to run the truck like the various fluids and fuel.
Many manufactures have started adding curb weight to the door jam sticker but if it’s not there you can sometimes find it on a sticker under the hood or online.
Curb weight is important because you need it to find your vehicle’s max payload rating. Curb weight can differ depending on your truck’s specific trim and model.
Gross Vehicle Weight. The GVW is how much your vehicle or truck will weigh with all the cargo and passengers loaded.
It’s easy to calculate if you know the curb weight, the weight of all the passengers combined, and the weight of your cargo.
Simply add them all together and you will know your GVW. You can also load everything up and take your vehicle to a scale to be weighed to find out exactly what the GVW will be.
Gross Vehicle Weight Rating.
This is one of the most important numbers to calculate how much a truck or vehicle can tow.
It’s how much the vehicle or truck is rated to weigh before becoming unsafe. It’s important to remember that towing a vehicle is going to add a lot of weight to your truck as well as passengers and cargo.
GCWR or GCVWR
Gross Combined Weight Rating or Gross Combined Vehicle Weight Rating.
This is another number you can use to determine how heavy of a trailer you will be able to tow.
The weight of your loaded truck and trailer cannot go over the GCWR.
The axle ratio is the number of rotations the driveshaft needs to make in order to spin the axle one time.
Lower axle ratios are better for fuel economy and higher axle ratios in the 3:73 – 4:10 are better for towing.
As an example, our Dodge Ram 2500 has the 3:73 axle ratio and has a GCWR of 17,000 lbs. If I had the exact same truck with a 4:10 ratio everything like the payload and GVWR would be the same but the GCWR would go up to 19,000 lbs. That’s why it’s important to know the axle ratio.
Most vehicles have that information on the sticker. It will the labeled as AL on the sticker followed by some numbers or letters. That’s the axle ratio code. You can normally look it up online.
In older vehicles like ours, you can either find it somewhere near the rear axle or if you’re lucky on a paper on the inside of the glovebox.
Gross Axle Weight Rating. How much weight each axle can handle.
The back is always going to be able to take more than the front. You won’t need this in your calculations, but it’s good to know what it means.
The maximum amount of people, cargo, and load you can add to your truck.
This is one of the biggest factors in calculating if your truck can handle a certain travel trailer or 5th-wheel.
You can sometimes find the payload on the door jamb sticker or online but you can also figure it out by subtracting the curb weight from the GVWR.
Words You Will Need To Know For The Travel Trailer or 5th-Wheel
Unloaded Vehicle Weight. More commonly known as the “dry weight” this is how much your trailer weighs without any cargo or full tanks.
It usually doesn’t include the weight of the batteries or propane tanks.
This is the most deceiving number in RV marketing. Most dealers are going to tell you the UVW because it’s the lowest number and it makes it seem like any RV can be towed by any size of truck or SUV.
It’s a good number to know but the weight of the RV when loaded down is more important.
Any travel trailer or 5th-wheel will also have a GVWR, this is how much the trailer can weigh in total. That includes full tanks and all your camping gear.
Normally the sticker on the side of the trailer where the GVWR is located will also tell you what the max weight of your cargo can be and how much a full water tank will weigh.
It may not seem like it but stuff weighs a lot. Unless you know exactly what you are going to be bringing with you it’s always safer to assume that your trailer is going to be as heavy as the GVWR when it’s finally loaded and the fresh water tank is full.
Hitch Weight/Tongue Weight
This is the second most important number for calculating the towing capacity of a truck or vehicle.
The hitch weight is how much weight is being put onto the truck. This number will be added to the final payload and GVW to find out if you are overweight or not.
It affects how much cargo you can load into your truck and can affect the number of passengers that can be brought as well.
A properly loaded travel trailer needs to have around 10% of the total weight on the hitch.
You can find your hitch weight a number of ways but the easiest is to get a specialized scale (click to view on Amazon).
If you don’t own the trailer yet you can do a quick calculation by taking the trailer’s GVWR and multiplying it by 0.1. This will give you a rough estimate of what the max hitch weight of a trailer could be.
For a 5th-wheel you will need to times the trailer’s GVWR by 0.2 (20%) because the hitch/tongue weight of a 5th-wheel is much more than a travel trailer.
But you probably won’t have as much cargo in the truck bed which means your truck may be able to handle a 5th-wheel anyway.
How To Calculate Your Truck’s Towing Capacity For A Trailer
The easiest way to do this is to write out all the specs and estimates then start doing the math part.
To make it easier to understand I’m going to show you the numbers for my 2004 Dodge Ram 2500 5.9L Diesel and my Heartland Prowler 27 BHS travel trailer.
Truck Numbers In Pounds
Curb Weight – 6,860 (what the truck weighs without cargo or passengers)
GVWR – 9,000 (how much it can weigh in total)
GCWR – 17,000 (how much the total weight of the truck and trailer combined can be)
Payload – 2,140 (found by subtracting curb weight from GVWR)
Maximum Trailer Weight – 10,000 (this number was found on the spec sheet online, it helps to give a general idea of how much a towed trailer could weigh but as you will see later that number isn’t always going to be a safe trailer weight)
Estimated Payload In Pounds
Passengers – 320 (2 people)
Cargo – 700 (We found our cargo weight by weighing our truck with us and all our stuff loaded onto it then subtracting the final weight from the curb weight and how much the passengers weigh.)
GVW (without trailer hitched up) – 7,880 (add curb weight with passenger and cargo weight)
RV Numbers In Pounds
UVW – 6,278 (dry weight of the trailer with no cargo or liquids)
GVWR – 9,000 (how much the trailer can weigh in total when loaded down)
GVW – 8,580 (found by weighing it on a scale, if you are looking at a trailer you want to buy just use the GVWR to calculate instead)
Hitch Weight – 850 (online the spec sheet for our trailer says it’s 750 lbs but we took 10% of the GVW to calculate more accurately. We suggest finding it out exactly with a scale but for doing calculations this is the next best thing. If you are looking at a 5th-wheel make sure to take 20% since the hitch weight will be more.)
Adding It All Up
Now it’s time to make sense of those numbers. To see if your truck can tow a certain RV safely or if your current RV is an ok weight you just need to do a little math to make sure everything checks out.
First, check the GCWR by comparing it with the GVW of the truck and the trailer added together.
Using my truck and trailer as an example: 7,880 + 8,580 = 16,460
If I compare that to the GCWR which is 17,000 I’m below the maximum combined weight rating but not by much.
This is a quick and easy way to get a general idea of what weight of a trailer you are going to be able to get but this isn’t the most important calculation.
The one that really starts to mess with the highest weight of a trailer you can safely tow is this next one that looks more closely at payload and your tow vehicles GVWR.
The final and most important calculation is:
Truck GVW (passengers + cargo + curb weight) + Hitch Weight = GVW When Towing
As an example, I’ll use the numbers from my RV and truck combo: 7,880 + 850 = 8,730
That number is how much your truck weighs in total when towing. It’s the number that cannot go over the GVWR of your truck.
For my truck, it’s 9,000 lbs which means I’m just 270 lbs under what my truck and trailer combo can weigh before I’m entering unsafe towing conditions.
How To Calculate If Your Truck Can Tow A Trailer You Don’t Own Yet
If you are trying to find a trailer your truck can tow safely you can use the GVWR of the travel trailer or 5th-wheel you are looking at to get a rough estimate of whether or not you will be able to tow it safely.
Compare Truck’s GVWR with Truck GVW + Hitch Weight (Trailer GVWR*0.1)
As an example, if I look at the Imagine 2970RL by Grand Design I see that its GVWR is 8,995 lbs. I can estimate that the hitch weight if loaded down properly to the max weight will be around 900 lbs (9,000*0.1).
If I add that to what my truck currently weighs when loaded down with passengers and camping gear my truck’s GVW will be 8,780 lbs. That’s still under my truck’s GVWR so I can technically safely tow that trailer.
5th-wheels have a much heavier hitch weight but they also make it harder to put a lot of cargo in the truck bed because that’s where the hitch is.
If I look at one of the smaller 5th-wheels made by Grand Design (Reflection 150 Series 240 RL) I see that the GVWR is basically 10,000 lbs. When properly loaded 20% of that weight should be on the hitch which means the hitch weight will be around 2,000 lbs.
I already know I’m going to have to greatly reduce the amount of stuff in my truck and take into account the heavy 5th-wheel hitch that will most likely weigh around 200 lbs.
That’s 2,200 lbs from the 5th-wheel alone. The payload of my Dodge Ram is only 2,140. That means I’m already overweight before I even put any passengers or cargo in the truck.
Of course, I could still tow the Imagine 5th-wheel safely if I make sure I don’t load it down to the max and limit the amount of cargo and passengers in the truck. My estimate is just when fully loaded to the GVWR.
Conclusions About A Truck’s RV Towing Capacity
It’s a lot of values and numbers but getting a good idea of what your truck or tow vehicle is capable of towing is a good place to start when you are shopping for a new travel trailer or 5th-wheel. You may not be able to safely tow the exact RV you want.
If you already have an RV it’s a good idea to weigh your truck and trailer fully loaded to make sure everything is where it needs to be.
You might have to limit the cargo in your truck bed or reload your trailer to get the hitch/tongue weight to 10% of the total trailer weight.
Why is it important not to go over the weights your truck and trailer are rated for?
The first reason is safety, overloading trucks and trailers causes moving parts like bearings, suspension systems, and tires to be weighed down more than they were designed to.
Tire blowouts, broken leaf springs, and bad bearing may happen more frequently, which can be hazardous especially when you’re driving fast.
Warranties might also be an issue. If your truck has a warranty and it becomes known that you are towing way over the limit that warranty may become void.
There are also legal reasons. It’s illegal to load a vehicle over the weight rating. If you are caught towing more than you’re supposed to, you will most likely get a large ticket.
It’s always better to be safe than sorry when it comes to towing heavy RVs.
In worst case scenarios you could possibly end up hurting yourself or others on the road. Being safe and avoiding breakdowns is always more fun anyway.
Have any questions about RV & truck towing capacity? Leave a comment below.