How to Pick the Right Tow Vehicle
How do you know that the vehicle or van you’ve chosen matches the other in terms of safe and legal towing? Here’s help…
by Colin Young, Caravan Council of Australia
Choosing the right tow-vehicle for a caravan or camper-trailer is just as important as selecting a caravan or camper-trailer that best suits your particular travel needs.
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It doesn’t matter whether you are looking for a tow vehicle or a van or trailer to tow behind a wagon or ute you already own, either way, it is vitally important to make a sound decision. This decision must be based on you doing sufficient homework, to ensure that the purchase is exactly what you want, to best suit your travel plans.
The number one requirement is that the combination is 100 percent legal (compliant), regarding masses and ratings, and provides the best possible safety on the road. Obviously, it is a major investment, so take your time to compare a number of different makes and models, noting the various specifications and ratings. Apart from the necessary technical and legal considerations, there are of course, numerous items that will be personal preferences.
In order to help you, this article provides a very comprehensive checklist to best ensure a specific tow-vehicle is suitable for towing a particular caravan or camper-trailer.
We reckon that you should use a separate checklist – and you can print these out – for each vehicle that you’re considering, listing your score for each item, then compare all final total scores.
RATINGS & MASSES
These are the most important legal and safety considerations.
While the law in some states may deem that the “actual mass” – not the “ATM – rating of the caravan/camper-trailer, that must not exceed the towing rating of the tow-vehicle, it can be extremely difficult to prove what the actual mass is.
The actual ball/coupling load exerted onto the tow bar at any time must not exceed the downward rating of both the tow vehicle and the tow bar… which are required to be provided by their manufacturers.
It is expected that the caravan/camper-trailer manufacturer will provide the maximum permissible ball/coupling load, that the vehicle was designed for, when loaded in a reasonable and typical manner.
Having a caravan/trailer sway – or jack-knife – is an extremely frightening and dangerous situation. There are three major items that determine
the stability/handling on the road:
(a) The length, weight and design of the caravan/trailer, (b) The manner in which it is loaded, and (c) The speed and road conditions.
It is essential that the ‘tail never wags the dog’… that is, it is important that the tow vehicle has the ability – primarily mass – to control the caravan/trailer, rather than the other way round. In addition to the legal requirements regarding ratings and masses, it is strongly recommended that, at any time, the mass of the tow-vehicle be appreciably more than the mass of the caravan/trailer. It is suggested that for added safety and peace-of-mind, the laden tow vehicle should weigh 30 percent more than the laden caravan/trailer.
It is important to obtain – in writing, typically the Owner’s Manual – details of any restrictions or conditions from the manufacturer of the tow-vehicle, regarding towing a caravan/trailer. Is there a stipulated maximum speed when towing? For particular towing ratings, are upgrades – such as oil-coolers, transmissions, brakes and/or suspension components – required?
AXLE – REAR
With solid (beam) rear axles most commonly used for tow-vehicles, recommendations should be sought – regarding vehicle handling, tyre life, etc. – if you are considering a vehicle with independent rear suspension.
Does the tow vehicle manufacturer (a) Require, (b) Recommend, or (c) Prohibit the use of rear axle booster-springs or airbags?
If required for towing, are they to be removed when not towing? If supplementary airbags are fitted, how are they to be attached to the chassis?
Does the tow-vehicle and/or the caravan/trailer manufacturer (a) Require, (b) Recommend, or (c) Prohibit the use of a WDH (weight-distribution hitch)?
If a weight distribution hitch is fitted, what rating should they be, and what setting should be used? Are there any restrictions or conditions regarding the use of
Does the tow-vehicle and/or the caravan/trailer manufacturer (a) Require, (b) Recommend, or (c) Prohibit the use of any other towing aids, such as mechanical
or electronic anti-sway systems?
From Isaac Newton’s laws, it must be appreciated that it takes much more time – and much more (over-taking) distance – to accelerate a combination, than it does to accelerate just the tow-vehicle, over the same speed range.
There is nothing more frustrating – and dangerous – than to be ‘stranded’, with not enough power on tap to get you out of a tight situation… such as when overtaking a slower vehicle, or when avoiding a collision, or just trying to get up to speed so as to prevent all of the motorists behind you from cursing you.
It is suggested that the ratio of kW : GCM (tonne) should be more than 25. For example, it is suggested that with a GCM Rating of 6.0 tonne, that the engine has a power output of at least 150kW.
Likewise, when towing, you need plenty of engine torque – or pulling power – to accelerate quickly. When you compare the performance of different engines, you will see that diesel engines have more low-down (rpm) torque available, than do petrol engines. This permits a faster acceleration from low speeds, with less gear-changes required.
It is suggested that the ratio of Nm : GCM (tonne) should be more than 65. For example, it is suggested that with a GCM Rating of 6.0 tonne, the engine has a (maximum) torque of at least 390Nm.
While LPG has many financial and environmental advantages, it is not always suitable for extended outback travel. The choice of fuel is therefore usually between petrol and diesel.
Considerations include the costs and availability in different regions of the country, any extra cost of the vehicle, and differences between servicing intervals and associated expenses.
FUEL ECONOMY Inherently, diesel engines have a higher efficiency – hence higher fuel economy – along with more pulling power than comparable petrol engines. Comparisons therefore need to be made between similar engines from various manufacturers.
Knowing the anticipated fuel economy (litres per 100 km), the driving range can be determined by taking into account the capacity in litres of the fuel tank(s) that are fitted.
Some ’vanners prefer automatic transmissions because they “do all of the work”, and make starting off from rest – especially uphill – much easier, with no worry about stalling the engine, or rolling backwards.
Some people prefer manual transmissions as they believe they have more “positive control”. Many automatic transmissions also have a manual over-ride, to provide the best of both worlds. The choice is personal, after evaluating the cost – and fuel economy – of each type of transmission, along with the towing recommendations, or conditions, from the tow-vehicle manufacturer.
It is important that the first gear is low (high reduction) enough to enable the combination to comfortably take off from rest up an incline.
2WD / 4WD / AWD
This is a very important consideration, depending primarily on what type of roads you will be travelling on. For paved and dry/hard/fairly-level roads, two-wheel-drive is fine. However, just one incident of being bogged, or an unintended off-road excursion, may well have you wishing that you had invested in the more expensive option.
All-wheel-drive, or four-wheel drive, provides major benefits in traction and safety, and is really a necessity when towing on off-road surfaces (mild, moderate, and certainly extreme) that are muddy, icy or are snow covered.
4WD / AWD provides additional benefits of better traction on bends, or wet and hilly roads.
Depending on whether your travel plans will be confined to on-road, or will include off-road, the choice will be quite simple. Of course your caravan or camper-trailer will need to have been designed and manufactured to reliably and durably withstand the same arduous conditions, so that you have a balanced combination.
UNDER-SIDE ANGLES Hand-in-hand with ground-clearance requirements for the combination, each vehicle needs to have comparable and adequate angles of approach, ramp and departure, so as best ensure you do not get stranded, or suffer any under-side damage.
A long wheelbase will provide more stability on straight roads, and will cause less axle load variations because of the coupling force on the tow bar. However, it will reduce the ramp-angle ground-clearance between the axles. A short wheelbase will generally provide easier handling on sharp winding roads, and rough dirt tracks.
It is more convenient to have identical wheels on both the tow vehicle and the caravan/camper-trailer, so as to enable the same spare wheel/tyre(s) to be suitable for both vehicles.
Identical means having (a) exactly the same rim diameter, width and off-set, and (b) exactly the same hub-mounting flange design, stud hole pattern, and stud diameter. However, often it is cost-prohibited, or not practical, to do this.
Likewise, it is more convenient to have identical tyres on both the tow vehicle and the caravan/camper-trailer. The choice of tyre is important, especially the tread pattern, which primarily depends on whether or not your travel plans include any possible sand, muddy or snow covered roads… or even wet grass.
Traction is vital under these conditions… it is pointless having plenty of engine power available if the tyres cannot obtain sufficient grip.
Many people prefer to use LT (Light Truck) tyres, rather than passenger-car tyres, on their caravan or camper-trailer, especially if any off-road travel is anticipated. While chunky tread tyres have major off-road advantages, their road noise and tread wear on paved roads will be worse. All-terrain pattern tyres are a popular compromise.
TOW BAR OVERHANG: Unlike fifth-wheelers where the articulation point is above the rear axle of the tow vehicle, caravans and camper-trailers have a significant disadvantage – regarding handling and stability on corners – because the articulation point (coupling) is quite some distance behind the rear axle of the tow vehicle.
Because of this, when the tow-vehicle is steered in one direction, the coupling moves in the opposite direction. This can cause an extremely dangerous situation if rapid corrective steering action is required to stop the caravan/camper-trailer from swaying.
The further the coupling is behind the rear axle of the tow vehicle, the worse the problem becomes, and with certain types of caravans, jack-knifing can occur very quickly… even at moderate highway speeds.
It is suggested that the tow bar overhang be no more than 30 percent of the wheelbase. (Refer to TB & WB in the drawing above right.)
COUPLING & HEIGHT ADR (Australian Design Rule) 62 prescribes legal requirements for “couplings” (which include balls, couplings, tow bars, safety chains, etc.) the different versions of which prescribe minimum and maximum heights of certain couplings above the ground, when the vehicles are fully-loaded.
In particular, there are specific limits for 50 mm ball-couplings because of their limited angles of articulation. Tow bars must have been strength-tested by their manufacturers, and have their two ratings – towing capacity and down load – marked on them.
You need to obtain confirmation from the manufacturers of both the caravan/camper-trailer and the tow vehicle that the coupling units comply with the ADR (and AS [Australian Standard} 4177) requirements… especially the coupling height (BH in the drawing). Confirmation is also required as to whether the height for 50mm ball couplings apply to all 50 mm ball couplings, or just fixed (non-pivoting) couplings.
Evaluate the warranty range – kilometres and years – and any conditions or restrictions that may affect your planned usage of the vehicle.
SERVICING COSTS Evaluate the required – and expected – servicing costs of the tow vehicle.
Are there any conditions regarding who may service it, or when, or where?
What are the labour charges for using the dealer’s servicing?
What is the cost of regular replacement service items?
What is the cost and availability of glasses and body components?
The choice of having air-conditioning or not is a personal preference, depending on the degree (pardon the pun) of comfort required. It is generally acknowledged that running an air-conditioner does not lower the fuel economy as much as driving with open windows.
OTHER OPTIONS Enjoying your travels is important… but not nearly as much as your safety. Tow vehicles now provide exceptional safety features, such as ABS (anti-lock braking system), ESC (electronic stability control), and traction control.
It is highly recommended that you select these features. They greatly improve road safety… but don’t rely on them to get you out of a hopeless situation. Double-check to ensure that they are full-compatible with any electronic stability units fitted to your caravan/camper-trailer. Also check that any electronic controls can be used while cruise control is activated. It is recommended that cruise control is not used when towing.
VAN DEALER ADVICE Ask the dealer of your caravan/camper-trailer if they have any (non-commercial) technical requirements or recommendations regarding the specifications for a suitable tow-vehicle for your specific unit.
Again, ensure that your dealer has supplied (in writing) all of the specific ratings and masses that you need to know in order to make sound decisions.
Check dealers, internet sites and newspapers for the same make/model vehicle of various ages and kilometres travelled.
MAKE & MODEL
Very strictly… a personal consideration!
What are the official Safety Ratings for the various crash tests? Hopefully you will never be involved in an accident, but if you are, high survival chances
Ask other ’vanners, and anyone driving the same make/model of tow vehicle that you are considering, exactly what they think of their vehicle, especially its suitability for towing.
Very simple… what is your budget? However, don’t skimp on safety just for a few dollars.
Before making a decision, test-drive each vehicle – ideally towing your ‘van – to see if you feel at ease driving it. Comfort, good all-round vision, and predictable controls are vital.
Carefully add up your scores for the various contenders. Hopefully, you will arrive at a meeting of heart and head choices and be sure in the knowledge that you’ve done everything possible to make the right choice.
Disclaimer: The above information is believed to be correct, and is offered in good faith. However, no liability whatsoever is accepted for any consequences arriving from the reliance or use of this information. None of the information is to be deemed to be legal advice. If you have any questions on any issues, consult an expert in the relevant field for advice.