The Complete Guide To Setting Up A Car To Be Flat-Towed Behind A Motorhome

Flat-towing a car behind a motorhome is a great way to bring extra transportation along when you’re traveling. We flat-towed our Honda CR-V behind our motorhome for over 20 years, so we’re well aware of the benefits of flat towing, and we’ve got plenty of experience to share with you in this guide. We’ll tell you everything you need to know and exactly what you need for this type of towing (also known as “4-down” towing).

Tag along and let’s set up your car for being flat-towed behind a motorhome.

What Is Flat-Towing?

Flat-towing is one way of towing a car behind an RV, where all four wheels remain on the ground. Also known as “dinghy towing,” this method of transporting a car involves attaching it to the RV via a tow bar, allowing it to roll along behind you (on all four wheels) as you drive.

One of the most significant benefits is that connecting and disconnecting is very fast and easy. Also, the equipment involved takes up very little space, unlike some other towing methods, such as dolly and trailer towing. The downside, however, is that not all cars can be flat-towed, and you can cause severe transmission damage if you try to flat-tow a car that isn’t designed for it.

You can safely flat-tow many vehicles with rear-wheel drive and a manual transmission, as well as cars with four-wheel drive and a manual transfer case. However, this isn’t always the case. For details, see our post on what cars can be flat-towed behind an RV.

The best way to determine if your car can be safely flat-towed is to consult your vehicle’s owner’s manual. If it says you can’t flat tow, don’t do it. Or at least not without modifying it first. In the post noted above, we discuss how some non-flat-towable cars can be modified to make them safe to tow, so if you’re interested in knowing more about that topic, be sure to have a look.

What Do You Need to Set Up a Car for Flat Towing?

Here’s what’s needed to get a car ready to be towed behind your RV with all four wheels on the ground.

Hitch Receiver and Adapter

First, of course, you must have a properly-rated hitch receiver on the rear of your motorhome. RV hitches are generally either frame-mounted or bumper-mounted. Note that if the receiver’s hitch height isn’t within 3″ of the height of your tow bar’s base plate, you’ll also need a hitch adapter to drop/raise it to the proper height.

Tow Bar

The tow bar’s job is to securely connect the front of your towed car to the rear of your motorhome. The two arms of the tow bar will connect to your car and can pivot side to side as necessary to offer smooth turning and towing. There are many different types of tow bars.

We highly recommend Roadmaster non-binding towbars and, specifically, the Nighthawk (their top of the line), which we used and loved for years. After we upgraded to the Nighthawk, we were so happy with it that we were able to arrange a special package for our readers which includes a FREE tow bar cover and hitch receiver lock.

So, when you buy a made-in-the-USA Nighthawk directly from Roadmaster’s factory in Vancouver, WA, just tell them you want the “RVgeeks Package” and they’ll include a FREE tow bar cover and hitch receiver lock in your order.

UPDATED NOTE: Roadmaster has continued to improve the Nighthawk since we got ours, and the LED lights on it are now multi-color and multi-purpose. In addition to lighting up yellow with your RV’s running/clearance lights, the Nighthawk now also has red lights that work with your RV’s turn signals and brakes, making it even clearer what your intentions are as you drive down the road.

Matching/Compatible Base Plate Kit

A compatible base plate must be installed on the towed vehicle (and professional installation is recommended). A base plate is a metal frame that bolts onto the front of your vehicle and typically has two receivers for connecting the tow bar arms.

Because the baseplate attaches to the towed vehicle’s frame and provides the connection point between the vehicle and the tow bar, it must be installed correctly. Each year, make and model of car requires a unique base plate, so you’ll need to be sure to get one that’s specifically designed to fit your car. Check with your installer and/or tow bar manufacturer for available base plate options.

Electrical Umbilical Cord

The umbilical cord is the electrical connection between the motorhome and the toad. It connects from the back of the RV to the front of the car, supplying brake, tail, and turn signal lights. It also carries the signal that powers the car’s auxiliary brakes (see below). Some setups also include power from the RV to the towed car’s battery to keep it trickle-charged (in our case, this happens through the Roadmaster Invisibrake supplemental braking system we had installed in our Honda CR-V).

Sometimes the umbilical cable comes with the towbar (as it does on the Roadmaster Nighthawk). If your RV already has a 7-pin trailer port, you may be set up for this connection already. If not, you may need something like this 7-to-6-pin cable:

Towed Car Light Wiring Kit

For safety, the lights of your towed vehicle need to be connected to and activated with the lights of your RV. For this reason, you’ll need to install a towed-car light wiring kit of some kind. The one below is a good example of a typical wiring kit.

Note that depending on the year/make/model of car you’re towing, you may also need additional wiring and/or lights installed. It’s also possible that you’ll need diodes or other electrical devices to ensure that signals don’t get crossed or back-feed into the motorhome. Lighting equipment is often installed professionally at the same time as the baseplate, but you can also install it yourself or use an external, magnetically mounted lighting solution like this one:

Safety Cables

Safety cables connect from the base plate to mounting points on the RV’s hitch receiver. Their job is to act as a failsafe connection in the improbable event that the towbar should separate from the motorhome or toad. Sometimes the safety cables are included with the tow bar package (as they are with the Roadmaster Nighthawk), but in many cases they’re not and need to be purchased separately.

Supplemental Braking System

A supplemental/auxiliary braking system may be optional, but may also be required in some states/provinces based on the size/weight of your towed vehicle. Either way, it is highly recommended because the weight of your towed vehicle can exceed/overload the capacity of the brakes on your motorhome.

A towed car brake system helps to manage the car’s weight, reduces stopping distance, and also brings the toad to a stop in the unlikely event of a breakaway. This is accomplished with the help of a breakaway cable that triggers the supplemental braking system in the towed car if it separates from the RV, bringing it to a safe stop on the road instead of allowing it to careen out of control.

The system we used is the Roadmaster InvisiBrake. We loved this unit for many reasons, including the fact that it pulls power from the parking light circuit to trickle charge the towed car’s battery while towing (as long as the motorhome’s parking lights are on). And, as the name implies, it’s effectively invisible (the components can be hidden away in your towed car’s interior) and requires no setup when connecting the car for towing.

We used this system in our CR-V for the last few years we owned our Class A motorhome. Combined with our Roadmaster towbar, we were more confident than ever that our Honda would safely and securely follow us wherever we towed it.

For much more information, see our full post on the Roadmaster InvisiBrake and have a look at our YouTube video:

Optional Upgrades You May Need for Flat Towing a Car Behind a Motorhome

So far, we’ve discussed the essentials you’ll need to safely and easily tow a car behind an RV. The following are some items you may want (or need) to consider, depending on your particular setup:

Drop/Rise Hitch

While flat towing, you want your tow bar to be mostly level. However, the maximum acceptable rise for most tow bars is only an inch or two. If your RV’s receiver sits significantly higher or lower than the mounting points of your toad car’s baseplate, you’ll need a drop or rise hitch to bring them into alignment.

Towed Car Protection

Towing a car behind a motorhome may leave it susceptible to damage from stones or other debris kicked up by the motorhome’s tires (especially when you’re traveling on unpaved roads). Fortunately, there are several good options available to protect a tow vehicle as it rides down the road behind a motorhome.

The best choice of protection may depend on the type of motorhome, tow vehicle, or tow bar that you have. See our post on tow vehicle protection for all the information you need on the variety of options available.

Battery Disconnect Kit

Some towed vehicles require the battery to be disconnected while towing. If this is the case with your setup, you’ll need to add a battery disconnect kit. These aren’t expensive or elaborate additions and you can easily install one yourself.

Simple Battery Disconnect Kit

Battery Disconnect Kit With Remote Switch

With this option, once the kit is installed, you won’t need to open the hood to manually disconnect your battery and can instead use the remote switch to disconnect & reconnect it as needed.

Battery Disconnect Kit With Wireless Key Fobs

For an even simpler installation (no wiring needs to be routed through the towed vehicle’s firewall into the passenger compartment), this version of the battery disconnect comes with a pair of remote control fobs, allowing you to connect/disconnect the battery with the push of a button.

Charge Line

Finally, a charge line may be needed to provide battery charging from the motorhome to the towed vehicle. This can be attributed to the numerous electronic components in cars these days. Some cars need to be towed while in a mode/state that leaves their electronics powered up during towing. If this is the case with your towed vehicle, having a means of providing charging to the car’s battery while it’s being towed can be very important. Otherwise, you could end up with a dead car/toad battery at the end of your drive.

Even if your car doesn’t require the ignition to be left turned on while towing, brake lights coming on as you drive may also be a drain on the toad’s battery (this depends on how your towed vehicle lighting kit is set up to operate).

We hope all of this information is helpful to you as you consider how (or if) you want to bring a car along with you as you travel. During the 20+ years we spent full-timing in our Class A motorhome, flat-towing was unquestionably the right method for us, as it is for so many others.

With the above systems in place, we safely brought our Honda CR-V along without a single problem over many thousands of miles.

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