Weights, Towing, and Capacity

January 3, 2020

Grab your RV dictionaries and calculators as we dive into everything you need to know about weights, towing, and capacity.

When purchasing a motorhome, you do not need to worry about having a vehicle to tow it. But you may want to tow a vehicle with your motorhome – or a boat or trailer with motorized toys on it. If you are wondering just what you can haul with your Thor Motor Coach motorhome, then take a look at the specifications of our flagship diesel pusher, the Tuscany; and our family-friendly Class A motorhomes, Hurricane and Axis.

Our featured motorhomes are ready to tow a trailer or vehicle with extra features to make towing easier such as back-up monitors, safety features and side-view cameras. Towing capacity can be a complex subject but we have attempted to explain some terms as well as some important equations.

Curb Weight

Curb weight is the weight of the motorhome with a full tank of fuel - be it gas or diesel. Curb weight does not include your cargo, your water, propane, or even passengers.

Unloaded Vehicle Weight

Unloaded vehicle weight, or UVW, is similar to curb weight. But for a motorhome, UVW is the curb weight of the motorhome WITH a full tank of LP.

Cargo Weight

Cargo weight is ALL the weight, every pound, added to the curb weight. This DOES include cargo, water, propane, passengers, and any aftermarket optional equipment.

When calculating your cargo weight, you need to remember water weighs 8.3 pounds per gallon, propane weighs 4.2 pounds per gallon. There is a difference in fuel weight: gasoline weighs 6 pounds per gallon and diesel weighs in a little more at 7 pounds per gallon.

Also take note here, when towing, trailer tongue load is also part of your cargo weight and we will talk about towing soon.

Occupant and Cargo Carrying Capacity

The occupant and cargo carrying capacity, or OCCC, is found printed on the yellow weight label inside your coach. You can find this on the entry door of the motorhome. This is important information. The little sticker lets you know how much weight you can add to your motorhome.    

Simply put, the OCCC is determined by subtracting the UVW of the motorhome from the GVWR of the chassis.

Gross Vehicle Weight Rating

You may have heard the term gross vehicle weight rating or GVWR. This is the MAXIMUM allowable weight of a fully-loaded motorhome. This number – along with other weight limits, as well as tire, rim size, and inflation pressure data – is shown on the vehicle’s Safety Compliance Certification Label. You’ll find this located near the driver seat.

Gross Vehicle Weight

Your gross vehicle weight (GVW) is the curb weight plus actual cargo, water, LP, and passengers. It is crucial to understand GVW is not a limit, it is not a specification. It is the actual weight you have when the motorhome is placed on a scale. This is simply how much your motorhome weighs as it travels down the road.

An important note, the GVW must never exceed the GVWR.

So your bays are packed and now you are ready to connect something to your hitch but you can’t just hook and go, there’s a lot to this. Let’s get into some towing terminology and look at the proper way to roll down the road.

One type is an unpowered trailer used to haul all your goodies, and designed to be pulled behind the motorhome. The typical trailer carries a portion of its weight on the trailer axle, and the rest of its weight is carried, through the trailer tongue, by the motorhome hitch.

Tongue Load or Tongue Weight

That leads us to tongue load or tongue weight. This is the amount of the trailer’s weight that presses down on the trailer hitch. Too much tongue load can cause damage to your suspension, drivetrain, and frame. It works the other way too. Not enough tongue load can cause instability.

You can find the maximum gross tongue weight listed on the motorhome hitch.

You do need to be sure the addition of tongue weight does not exceed the key towing weight limits - that’s your GVWR and rear axle GAWR. You can find GVWR and GAWR on the motorhome’s Safety Compliance Certification Label.

If you are above either of these limits, your safest bet is to go with a smaller trailer.

Something else to think about is the way you have the trailer loaded and if it is going to affect your tongue weight. If you have too much tongue weight, shift some of the cargo to the rear inside the trailer.

When it comes to hitches, DO NOT USE a weight-distributing or load leveling hitch with your motorhome. It is not capable of transferring any useful amount of weight from the rear axle to the front axle or limiting up and down hitch movement, and you could end up damaging the hitch, the receiver, the rear overhang of the motorhome frame, or the trailer frame itself.

How about hooking up a toad or dinghy vehicle?

Toad is a slang term for “towed automobile”, typically a car or SUV you pull behind the motorhome. It involves attaching a tow bar to the vehicle to roll along behind the motorhome on its own four tires. You may have heard it called four-down towing or flat towing.

Unlike a trailer, a toad places very little tongue load onto the motorhome hitch.  But only certain vehicles can be used as a toad behind a motorhome so you need to check the car’s owner manual for all the details and specifications.

The maximum loaded trailer weight or towing capacity, is the highest possible weight of a fully-loaded trailer or toad the motorhome can tow - based on a minimally loaded motorhome GVW. 

You may want to hit the nearest scale for our next few items.

Gross Axle Weight

Gross axle weight (GAW) is the total weight placed on each axle, both front and rear. To determine the gross axle weights for your motorhome and vehicle or trailer combination, take your loaded RV and tow vehicle, or trailer, to a scale. With the trailer attached, place the front wheels of the motorhome on the scale to get the front GAW. For rear GAW, weigh the motorhome with the trailer attached, but with only the four wheels of the motorhome on the scale. Subtracting front GAW from that amount gives you rear GAW.

Gross Axle Weight Rating

Add an R to the end and now you have (GAWR) – your gross axle weight rating.

This is the maximum weight to be carried by a single axle. On a motorhome, the rear axle GAWR is larger than the front axle GAWR. These numbers are also shown on the Safety Compliance Certification Label. The total load on each axle GAW must never exceed its GAWR.

Gross Combination Weight

The gross combination weight (GCW) is the weight of the loaded motorhome (GVW) plus the weight of the fully-loaded trailer or toad. It is the actual weight you get when the motorhome and trailer combination are weighed together on a scale.

Gross Combination Weight Rating

The gross combination weight rating (GCWR) is the maximum allowable weight of the motorhome and the loaded trailer or toad that the motorhome can handle without the risk of being damaged. GCWR is a value determined by the chassis manufacturer and is dependent on the GVWR, engine size, and axle ratio of the motorhome chassis. GCWR weight ratings are found in the towing guide or spec sheets published by the chassis manufacturer. GCWR information for current model year motorhomes can also be found on the specs page of the Thor Motor Coach website www.thormotorcoach.com.

Here’s an important note: the motorhome’s brake system is rated for operation at the GVWR, not the GCWR. A supplemental braking system should be used for safe control of towed vehicles and for trailers weighing more than 1,500 pounds when loaded. The measured GCW must never exceed GCWR.

So are you ready for a little math? Here’s what you need to add or subtract to determine some important capacities.

For your gross vehicle weight (GVW), it is:

              Curb Weight + Cargo Weight + Water Weight + LP Weight + Passenger Weight + Tongue Weight

REMEMBER - GVW must not exceed GVWR.

To figure out your gross combination weight (GCW), it is:

              GVW + Trailer Weight or Toad Weight

And remember GCW must not exceed GCWR.

To get your towing capacity, it is simply:

              GCWR – GVW.

Be sure to also follow the maximum gross trailer weight rating that is shown on the motorhome hitch itself. Your towing capacity may be limited by the hitch rating.

And one last important note: when towing, remember to always stay within your GCWR, GVWR, GAWR and hitch ratings to safely tow a trailer or toad with your motorhome. 

Now that you have all the info, load up, hit the road and make some memories. For more owners’ resources, visit thormotorcoach.com.

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