Tow vehicle buying tips

Making the choice about which tow vehicle is the right one to buy is often a hard one because you’re not going to find many car dealers that will let you hitch up your caravan to try it out.

While we can help with our dedicated towing tests, showing how a vehicle tows in the real world, there are also technical specs that give you clues to whether a vehicle is likely to be a towing hero or not.

Like everything, you will have to make compromises when choosing a tow vehicle. A big, heavy 4WD might tow really well but might be hard to live with during the daily urban grind. Yet if you’ve got a big, heavy van, a nimble city car isn’t going to cut it.

What will ultimately make or break towing rig balance is load placement, but there are a few tow vehicle specifications that will indicate whether it’s likely to be a stable platform to start with.

You want as long a wheelbase as possible and as short a rear overhang as you can find for better towing stability. If you have a tow vehicle that’s short on wheelbase and has a long rear overhang (and/or has a towbar design that has the towball sticking out for miles) it’ll allow the caravan to have more leverage to make the vehicle yaw (sway).

A live rear axle is usually stronger and more consistent for load carrying than an independent suspension design, including when you’ve got the combination of a heavy towball download and a loaded vehicle. Because the live axle is tougher (and more often than not fitted to load-carriers like utes), there is usually a higher axle load limit than independent designs.

Generally speaking, tyres will wear more evenly with a live axle than with an independent set-up when under load because the wheel’s relationship to the road never changes. That is not always the case with some independent suspension designs, as they can end up causing accelerated tyre wear with negative camber when compressed, such as when towing.

With leaf-spring rear axles, there are fewer bushings to wear out too, and those there are – because of the tougher nature of the suspension application – tend to last longer.

Caravans are only getting heavier as buyers demand more features, but you should be realistic about the vehicle’s maximum towing capacity. It’s not worth loading a van so it is as heavy as the vehicle can tow down to the last kilogram. You need a safety margin, and you might need to pay for it with a bigger, heavier and more expensive tow vehicle.

It is always a good idea to buy a vehicle with as much towing capacity as you can get, though, even if you don’t think you’ll ever need it. If your van won’t ever weigh more than 2300kg fully loaded, you can buy 4WDs that have a 3500kg maximum capacity. The extra 1700kg isn’t a waste – the higher the capacity, the better, generally speaking, as the vehicle will have more power in reserve and more weight to make a more relaxed towing platform.

It’ll also give you some leeway if you upgrade to a heavier van later.

Try to buy a vehicle that has ten percent towball mass (TBM) download capacity (of maximum towing capacity). Don’t assume that the vehicle you’re considering does have the 10 per cent TBM, as not all do.

Two examples come from Mitsubishi and Nissan. The Mitsubishi Pajero has the 10 per cent TBM – but only up to 2500kg. If you’re towing between 2500kg and 3000kg with a Pajero, TBM is reduced to 180kg.

A number of Nissan vehicles have a reduced TBM when the vehicle is at or near maximum GVM. For example, the Y62-series Patrol TBM maximum is 250kg at GVM; reduce payload by 130kg, and maximum TBM is 350kg (and therefore 10 per cent of the Y62’s 3500kg towing capacity).

The checklist:

Some manufacturers have a very low TBM download capacity – much less than 10 percent – either because the vehicle’s manufacturer discovered during development that the towbar or the chassis is not up to the job, or it was engineered that way for markets (such as Europe) where such a TBM is not necessary.

European vans only require up to five per cent TBM, so some European vehicles can has as little as an 80kg or 100kg TBM maximum.

Don’t forget that TBM is part of the vehicle’s payload, and also a proportion of the vehicle’s rear axle load. These have to be factored in your towing weight calculations. Better to find these won’t work for your van by looking at the vehicle’s tech specs before you buy than after.

Generally speaking a vehicle will tow better if it is heavier than the caravan it is towing. While many vehicles are perfectly legal towing a trailer weighing more than they do, don’t assume you can buy and load up the heaviest, biggest caravan you can buy and that the vehicle will tow it like a champ.

Dual-cab utes are the main culprits here; most weigh not much more than 2000kg but some are rated to tow 3500kg. Some are really good tow vehicles, but a heavy van will more easily become unstable of the much lighter tow vehicle has to swerve to avoid an obstacle, for example.

Don’t forget to check the towbar’s towing maximum if you’re buying used. Towbar capacity can sometimes be rated lower than the vehicle’s maximum towing capacity.

Even though the separate chassis is really old-school in the passenger car world, commercial vehicles still use the this design for a reason – it is typically stronger than a monocoque body. That doesn’t mean monocoque is bad, (the long-lived Pajero is a case in point) but for heavy hauling, a separate chassis, only found on large 4WD wagons or utes, is the best bet.

Whether you should buy a diesel or petrol tow vehicle comes down to many factors but generally the diesel engine has better load-lugging torque and is much more efficient.

Towing a heavy caravan puts a lot of load on an engine and while a petrol engine of large displacement and with good torque output will handle it comfortably, it will consume a lot of fuel doing it. You can expect at least 50 per cent more fuel use when towing a full-size heavy van with a six or eight-cylinder petrol engine vehicle than when travelling solo.

The modern turbo-diesel engine is the best compromise for towing, with its strong mid-range torque that makes towing relatively relaxed. The added bonus is fuel consumption will be better than a petrol vehicle, with only perhaps a 25 per cent higher thirst than when cruising without a van.

The only negative with a diesel is the potential for expensive repairs if it gets a dose of contaminated fuel. The injectors and fuel pump of high pressure common-rail diesels don’t cope well with that.