Did you know that a Vehicles Manufacturer has recommended axle weights for their vehicles?
You can usually find it in the Owner’s Manual – you know that book that’s in the glove box that’s 500 pages long and we never read…
You have to search for it – but there is manufacturer’s recommendation for axle weights loads which can have serious ramifications if you exceed these weight limits.
Firstly if you exceed them you may break something – at a minimum, pretty inconvenient and it also could be expensive.
If you’ve exceeded that weight – then the manufacturer may void your warranty. Getting more expensive and even more inconvenient.
And if your insurance company deems that the excessive weight contributed to an accident – then you may lose your insurance. And this is the most expensive option.
Got you attention? Good.
We’ll use a 2020 Ford Ranger for example.
The GVM is 3200 kg
The maximum rear axle load is 1850 kg
The maximum front axle load is 1480 kg
So the first thing you may notice is that they don’t agree – 1850 + 1480 = 3330 – that’s 130 more than the GVM.
So you can’t have both axles maxed out and still be under GVM.
So what is the impact of a load in the back of a Ford Ranger
Any load in the front part of the Tray goes 100% on the back axle – because the load is directly over the back axle (wheels).
But here’s the real killer – Whatever weight you put further past the back axle, the higher the % increase it will have on real load on back axle.
Any load in the back part of the tray is going to impact at least 125% of its weight on the back axle.
So load up a fridge and beer weighing 40 kg behind the wheels – and you probably adding 50 kg to the back axle.
Whatever you put on the tow bar – because of it’s distance behind the rear axle (wheels) impacts around 150% of its weight onto the back axle.
But – how can it put more weight on the back axle than it weighs, I hear you ask?
Good Question.
The answer is that when you put weight behind the back axle – due to the pendulum effect – and the fact that the back axle is acting as a pivot for the load, you take weight off the front axle.
So if you put 300 kg on the tow ball – you could put 450 kg on the back axle and you take up to 150 kg off the front axle.
So you have added 300 kg to the vehicles overall weight (GVM) it’s just distributed unevenly. (You don’t have any control over that unless you buy a 5th wheeler…).
So the heavier the caravan – the heavier the tow ball – the more drastic the effect on the back axle.
So you may still be under GVM – but you may be over on the back axle – and therefore much lighter on the front axle.
Warning – A too heavy rear axle and light front axle can result in poor steering response and poor front braking.
Especially in an emergency situation or on wet roads.
At Check Weight because we weigh each wheel – we can tell you your wheel, axle and vehicle weights. A lot of public weighbridges will only tell you what the vehicle weight is in total – not where that weight is.
And this is also why it is very important that you weigh your vehicle ATTACHED to the Caravan.
Weighing them separate and adding them together only gives you half the story!
And YES we are seeing a lot of vehicles at or near their GVM limit – but over their rear axle load limit.
In the following example Check Weight weighed the vehicle (in this case not a Ford Ranger) and the rear axle weight increased by 148% after the caravan was hitched to the tow vehicle.
If you would like any more information on Maximum Axle Loads please email Jeff @ Check weight on info@checkweight.com.au
and if you noticed that in the above example there is a 20 kg difference in the tow ball weight – well that’s because the weigh pads weigh in 10kg increments and the tow ball weigher in 0.5 kg (therefore more accurate) – and I’ll go further into that, in another blog !
And we will also cover off Weight Distribution Hitch (WDH) in a future blog !
