Shift that flab

In 2008 we officially became the fattest nation on Earth so we all know that we’re in the midst of an obesity epidemic and that its onset seems to have run parallel to our fascination with televised sport, game consoles and fast food.

Even the motoring world has had to adapt to the increasing BMI of occupants with bigger seatbelts and larger cabins in smaller cars and there’s even talk of child restraints being super-sized.

With the release of the 200 Series Landcruiser you might have thought that they’d be making room for all that extra flab too, but not so.

You see whilst the vehicle’s kerb weight has ballooned out by 235 kg to 2700 kg, its load carrying capacity has reduced by 295 kg to 600 kg.

This means that if you loaded up your 200 Series with 8 standard men weighing 70 kg for a spot of fishing there would be only enough room for the tackle, one slab of beer and the nibblies before the vehicle is legally overloaded.

You’d have to use the bait, drink the beer (then urinate) and eat the food (then defaecate) to have any chance of loading up your catch for your journey home.

And even though the Landcruiser is rated to tow a trailer of up to 3500 kg in weight, 10% of that weight is meant to rest on the towball.

That’s another 350 kgs loaded onto the vehicle so sorry there’s no way that you can legally take your boat with you on this fishing trip.

The ball weight can be manipulated by shifting the trailer’s load forwards or back across the axle, but that 10% figure on the towball is still essential for the rig to handle safely.

All of this can be rather complex as a colleague who’d bought a turbo-diesel Discovery Series 3 to tow his boat found out.

The car is rated to tow a hefty 3500 kg and the ball weight is rated at 250 kg so you wouldn’t think he’d have any trouble towing his 2000 kg boat even with it full of fuel and gear.

With the towbar tongue coming out from below the under-slung spare the series 3 Discovery has a standard towball height of 410 mm.

Air suspension will lift this by 50 mm once you’re underway, but the height of the hitch on the drawbar of my colleague’s trailer meant that he wanted to lift the whole lot up a bit more with an aftermarket towbar tongue.

The only problem was that the new tongue was only rated to 1500 kg and the boat weighs more than that.

He eventually solved the problem by using an extended ball which brought the centre up by 50 mm and this didn’t affect the vehicle’s load carrying capacity.

Remember that some manufactures (eg Subaru) may specify a lower speed limit when towing and that some recommend using a load levelling hitch (eg Jeep) and some recommend not using them (eg Nissan).

And as we’re all getting fatter it may not be too long before we’ll be weighing our hand luggage before we drive off.

For those grey nomads amongst us here is the lexicon of towing:

Tare weight (T): Sometimes called the unladen weight and is the weight of an empty vehicle.

Kerb weight (K): The tare weight including a full tank of fuel, oil and coolant together with the spare wheel etc., but it does not include the weight of personal goods or occupants.

Ball weight (B): Ball weight refers to the weight on the front end of the trailer carried on the towball and not carried over the axles. This can be measured at a weigh bridge or in the surgery by unhitching the trailer and resting the jockey wheel on a set of bathroom scales.

Gross vehicle mass (GV): The maximum allowable total mass of a fully loaded motor vehicle, consisting of the tare (mass of the vehicle) plus the load (including passengers and the ball weight).

Aggregate trailer mass (AT): The total mass of a fully laden trailer.

Gross trailer mass: The mass supported by the axles of a loaded trailer, i.e., gross trailer mass is the aggregate trailer mass minus the ball weight.

Gross combination mass (GC): The maximum allowable total mass of a fully loaded motor vehicle and its trailer.

Car T K GV AT B P GC
LandCruiser 100 2.3 2.36 3.26 3.5 0.35 0.89 6.76
LandCruiser 200 2.54 2.7 3.3 3.5 0.35 0.6 6.8
Discovery 3 HSE 2.7 DT 2.44 2.71 3.23 3.5 0.35 0.51 6.73
Patrol 3.0 TD DX 2.35 2.44 3.02 2.5 0.2 0.58 5.52
Patrol 4.8 Ti 2.41 2.47 3 3.5 0.2 0.52 6.21

All weights measured in metric tonnes. P refers to payload.

Safe motoring,
Dr Clive Fraser

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    Medical Motoring is an online record of the articles written by Dr Clive Fraser and published in the Australian Medicine magazine by the Australian Medical Association.