So, straight off the bat there are five dominant measures that all revolve around towing capacities, that immediately come into play. Namely: 1. Gross Vehicle Mass (GVM) This is the maximum your vehicle can weigh when fully loaded as specified by the manufacturer. You will usually find this GVM figure on the vehicle's weight placard (generally found in the driver's door opening) or in the owner's manual. So GVM is the Kerb Mass plus any accessories fitted after the vehicle was manufactured, driver, passengers, luggage, pet dog, esky, tool kit and whatever else you're taking with you. And if you're towing something, GVM also includes the Tow Ball Download (TBD). 2. Gross Trailer Mass (GTM) This is the maximum axle load that your trailer is designed to carry as specified by its manufacturer. It is the combined weight of your trailer and its payload but does not including the Tow Bar Download. The GTM is usually displayed on the trailer or in the owner’s manual. 3. Gross Combined Mass (GCM) This is the maximum weight allowed for your vehicle and trailer combined, as specified by the tow vehicle's manufacturer. This is where you must pay close attention to your vehicle's GVM and your trailer's GTM, because those two figures determine the GCM and one directly affects the other.4. Tow Ball Download (TBD) The amount of weight on your tow bar is crucial to safe and efficient towing and needs to be mentioned here. Any quality tow bar will have a placard or similar showing the maximum tow bar capacity (kg) and maximum tow ball download (kg). Make sure the tow bar you choose is designed specifically to suit your vehicle and your towing capacity requirements. Typically, the TBD should also be around 7 - 12 percent of the Aggrigate Trailer Mass (ATM), Ideally 10%, which for peace of mind can also be calculated using the ATM and TBD figures as shown here: [ TBD divided by ATM x 100 = TBD percentage of ATM ].
5. Kerb Weight This is the same as Tare Mass, but with a full tank of fuel and without any accessories fitted (bull bars, tow bars, roof racks etc). Think of it as your standard vehicle literally parked at the kerb and ready for you to get in and drive away.
Now here is the kicker. The Toyota has a GCM of some 6800kg and the Ford only 6000kg. That is a whopping 800kg difference. Now let us assume that we need to also carry 2 x passengers = (140kg) + vehicle accessories, bull bar, Tow bar, roof rack and set of draws etc = (120kg) + cargo, fridge with food and drinks, tools, table and chairs etc = (60 kg), and let us not forget a TBD, 10% of our ATM = (350kg). All these extras give us an additional payload of 670kg.
So, what is the result?Looking at the chart you can see that with an average payload of 670kg the Land Cruiser comes in some 75kg short of legally towing that 3500kg caravan. GCM (6800) -Kerb Weight (2705) – Payload (670) = Legal towing capacity (3425). To further complicate the issue the allowable payload is also 35kg over the specified limit. Ooops!
The Ranger on the other hand is 399kg under its specified payload limit for the tow vehicle. Good start. Unfortunately, the Ranger can now only now manage to legally tow a caravan weighing 3199kg. GCM (6000) -Kerb Weight (2131) – Payload (670) = Legal towing capacity (3199), even with its generous 1069kg payload allowance.
The upshot is you can always get a GVM upgrade for the Land Cruiser to raise the payload allowance by around 370kg and still legally tow 3500kg. Unfortunately, on the other side of the coin there is no remedy available for the Ranger to raise the GCM, so the legal towing capacity remains at 3200kg with a 640kg payload (adjusted for a reduced TBD of 320kg).
Just imagine if we wanted to go that little bit further how the results could be impacted if we decided we wanted other accessories. Things like a long-range fuel tank, bike carriers and off course a bike or two, or in the case of the Ranger a canopy on the tub. Things could really get scary quickly.
Hopefully, this demonstrates the real need to do your homework when it comes to matching a caravan and tow vehicle. It is the only way to ensure you select an appropriate vehicle, fit to do the job you require of it.Next time we will get into tow vehicle axle weight limits and how to load your tow vehicle and caravan.