Why 4500kg tow ratings are misleading

They’re bold and brassy and seem to be built big and tough enough to haul a house across the prairies.

We’re talking about those utes a few steel-cap boot sizes up from the Toyota HiLux and Ford Ranger dual-cabs – that is, the full-size American pick-up trucks such as the popular RAM 1500 and Chevrolet Silverado.

These giant utes have become go-to vehicles for any Aussie who wants to tow up to 4500kg and look good doing it.

But can they really tow 4500kg?

As it turns out, not everything is as it seems...

As with any towing scenario we lay out for you, it has to carry some assumptions. Only you can know what your vehicle and trailer weigh as you intend to tow, all loaded up.

That means not guessing what it all weighs but getting the rig measured at a public weigh station or engaging the services of a private weight scale operator.

But to get a good idea of what the big utes can really tow, we have collated all the towing weights of five US pick-ups to calculate their real-world towing capacity when lugging a full 4500kg behind them.

Here we’re talking about the officially backed big fellas of the ute world, led by the DT-series RAM 1500 and DS-series RAM 1500.

The RAM 1500 has been joined by the Chevrolet Silverado – both are converted to right-hand drive by Walkinshaw Automotive in Melbourne – while Ford will climb onboard next year using its own partner with the F-150.

The Blue Oval-backed Ford F-150 will be locally converted in Melbourne by Thai firm RMA in two model grades – XLT and Lariat. Fitted with a 298kW/678Nm 3.5-litre V6 twin-turbo petrol engine and 10-speed auto, Ford Australia has already confirmed a 4500kg towing capacity for the F-150.

We expect the 2023 Ford F-150 XLT will kick off at about $120,000 plus on-road costs, with about $5K extra for the upper-spec Lariat.

Toyota Australia is also putting together its own program with the help of Walkinshaw that could see the Toyota Tundra pick-up in showrooms in 2024.

It will be powered exclusively by a 325kW/790Nm 3.5-litre V6 twin-turbo petrol-electric hybrid powertrain.

In contrast, the RAM and Chevrolet 1500 models both use a traditional big-bore V8 petrol engine, a 5.7-litre in the case of the RAM 1500 and 5.2-litre for the Chevy.

We haven’t included the more heavy-duty 2500 and 3500 versions, as that requires roaming around the minefield of needing a truck licence to drive them, and not all the brands offer these heavier haulers anyway.

Ford and Toyota specs are only our estimates based on similar US models. This is because the local Aussie models – and some of their specs, such as maximum weights – are some way off being released.

Where possible, we’ve chosen the lower-spec model available (or the one that’s going to be available here) so we could shine the best possible light on towing capacity for the big utes.

For a country claiming a ‘she’ll be right’ attitude, Australia has a lot of rules and regulations, especially where safety is concerned – and that’s not a bad thing.

Relevant here is that you can’t drive a vehicle that has a gross vehicle mass (GVM) of more than 4.5 tonnes on a car driving licence and you can’t tow anything heavier than what the vehicle manufacturer specifies without breaking the law.

GVM is the total maximum the vehicle can weigh by itself, without a trailer.

Any vehicle towing a trailer with an aggregate trailer mass (ATM) – that’s the total mass of the trailer when carrying the maximum load recommended by the manufacturer – of between 3500kg to 4500kg also must do so with a 70mm-rated tow ball, instead of the standard 3500kg-rated 50mm ball.

The tow bar, trailer coupling and chains must be rated to 4500kg. That’s why you don’t see many 4500kg tow-capable vehicles or trailers up to 4500kg ATM; it is easier to engineer and comply vehicles and trailers only up to the 3500kg federal standard requirements.

This leaves anyone wanting to haul a bit more than 3500kg in a quandary. If you have a trailer that actually weighs more than 3500kg and up to 4500kg as towed (such as a trailer boat or large off-road caravan), there are slim pickings for vehicles that can legally do the job.

You will need to buy a light truck or a US ute such as the five we have assembled here.

The catch with some of these 4500kg-rated US utes is that you can’t necessarily tow 4500kg and carry much of anything in the vehicle at the same time.

While some have an impressive payload maximum, they don’t look quite so great once you minus the whopping 450kg of tow ball mass (TBM).

In the table below you’ll see the basic weights you need to know.

Towing capacity is 4500kg, with a maximum 450kg TBM for all of them. The rest of the towing specs needed to calculate real towing capacity are kerb weight, payload, GVM and gross combination mass (GCM), which is the maximum the vehicle and trailer can weigh.

Here we’re assuming a 10 per cent TBM (in this case 450kg) for all of the pick-ups to see what that leaves you for actual, useable payload (remembering that as soon as you plonk the trailer on the ute, that nose weight on the tow ball becomes part of vehicle payload).

This is before considering what 4500kg behind these utes does to other weight restrictions.

The useable payload column on our table shows just how little weight remains once you have the 450kg of tow ball mass pushing down on the ute – from 380kg in the RAM 1500 DT to a much more respectable 502kg for the Ford F-150.

The point is that while some of these utes start out as one-tonners (or close to it), they certainly are not any longer once a heavy trailer is pushing down on their tow bar.

Regardless of what mix of trailer nose weight and your actual payload (people, accessories, luggage, anything you add to the vehicle from empty) that makes up your final payload, there is still only so much your trailer can weigh before you hit the GCM limit.

So in column six, we’ve subtracted GVM from GCM to see what’s left as the maximum weight that can be resting on the trailer wheels. This is called gross trailer mass (GTM).

The GTM of the trailer is transmitted to the ground by only the caravan tyres and excludes the mass distributed to the towing vehicle through the coupling (remembering that this coupling weight becomes part of the ute’s GVM when hitched up).

In this scenario, if you assume that a 4500kg trailer has 10 per cent tow ball weight (450kg), that would mean the weight over the trailer wheels would be 4050kg (assuming the ute has legal capacity for this amount with its GCM).

However, not all these utes can do this. Only two of the five – the Ford F-150 and Toyota Tundra – can tow the full 4500kg. In fact, they have capacity within their GCM to tow more, if it were not for Australian regulations restricting it to 4500kg.

Meanwhile, the DT-series RAM 1500 DT has just 3787kg before it hits GCM, and the DS-series RAM 1500 has 4263kg.

Of course, a trailer with 4500kg GTM (as noted in the table for the Ford and Toyota) will either have a total weight of 4500kg (meaning it has zero tow ball mass) or must be overweight, which is not what we are suggesting here.

This table simply shows there is a more than comfortable safety margin for towing with these two big utes.

In the last column, we’ve assumed that towing the full 4500kg (or very close to it) is the main priority, rather than having as much useable payload as possible.

So what does that leave to put in the truck to not exceed GCM?

Here, there is just 117kg of payload available in the RAM 1500 DT, and 120kg in the Chevrolet Silverado. The Ford F-150, RAM 1500 DS and Toyota Tundra can all tow up to the remaining payload available once you account for tow ball mass (here, as elsewhere in this article, we’ve assumed a TBM of 450kg).

This is a problem, because if, say, you weigh 80kg and your partner weighs 50kg, you had better forget bringing along your sunnies and boiled lollies in the truck. Technically, legally, you are already driving an overweight vehicle once you and your partner climb aboard.

Although the newer utes are getting better at towing the big stuff, never assume they can.

If you do the maths as we have here, you’ll soon see that some of the big American pick-ups are not as great towing heavy gear as others.