The answer is yes. There would be only 200kg left for the vehicle - unless your car happens to be like mine where the manufacturer (BMW) has specified a different rear axle load limit when towing (1490kg) to when solo (1330kg)
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The answer is yes. There would be only 200kg left for the vehicle - unless your car happens to be like mine where the manufacturer (BMW) has specified a different rear axle load limit when towing (1490kg) to when solo (1330kg)
Basically yes. But as I pointed out above its a question of levers and loads. If a nose load produces a force 100kg at the ball, the leverage it offers over the rear axle will apply more than 100kg to the axle - exactly how much depends on the geometry of your car. It is a real load and it would be detected by and axle weigh bridge.
The calculation is relatively simple, you need to know the tow vehicles wheel base (WB) and the tow vehicles over hang distance from the rear axle to teh ball (OH) and the applied nose load (NL)
The leverage or the Torque(T) of the nose load on the front axle is (WB+OH) x NL = T
and the load on the rear axle will be T/ WB
If for example a tow vehicle had a hitch overhang of 1m and a wheel base of 3m that would mean 100Kg at the hitch would produce (100kg x 4m )/3m = 133.3kg at the rear axle. So your actual load capacity in the rear of car is down by 33.3kg
However the reverse is true of the front axle which will be unloaded by the same 33.3kg so your over all weight (including nose load) is the same.
Most people are not usually fully exploring the load capacity of the car so the issue is rarely a real concern.
That’s a very useful feature first I have heard of that. Are the limits shown on the cars VIN plate? Also is it specific to your model and year or would other BMWs have the feature. I wonder how many BMW caravan tuggers are aware of it.
So we’ve been to put the order in for our replacement van today. (hooray)
On the way back we were passing the public weighbridge at the West Yorkshire trading standards place in Gildersome.
So I had to have a go.
I made Mrs Ste stand outside and I also took out the dog crate plus the car had less than a quarter of a tank of fuel.
Bearing in mind the published kerbweight is 1685kg, here’s what came up:
(Previous readings from weighbridge in Hull are in brackets)
Front axle 1040kg (1050kg)
Rear axle 790kg (810kg)
Gross 1830kg (1860kg)
So fuel tank almost empty and 60L of diesel weighs about 50kg so that about works out right because it wasn’t full when I did the first weigh.
So with 2 comparable readings under my belt I’m now confident that neither Towsure nor Mitsubishi have got it right and that using my figures and staying well within the plated limits of both towcar and van, I can confidently drive our new outfit next month.
On the way back we were passing the public weighbridge at the West Yorkshire trading standards place in Gildersome.
So I had to have a go.
I made Mrs Ste stand outside and I also took out the dog crate plus the car had less than a quarter of a tank of fuel.
Bearing in mind the published kerbweight is 1685kg, here’s what came up:
(Previous readings from weighbridge in Hull are in brackets)
Front axle 1040kg (1050kg)
Rear axle 790kg (810kg)
Gross 1830kg (1860kg)
So fuel tank almost empty and 60L of diesel weighs about 50kg so that about works out right because it wasn’t full when I did the first weigh.
So with 2 comparable readings under my belt I’m now confident that neither Towsure nor Mitsubishi have got it right and that using my figures and staying well within the plated limits of both towcar and van, I can confidently drive our new outfit next month.
No, of course it's not on the VIN plate because there simply isn't the space there to show two values and above all, to specify which value applies under what conditions. The VIN plate only shows the lower (solo) figure. The value applicable to towing is, however documented in the type approval Certificate of Conformity.
I agree with you that probably not many BMW caravan tuggers are aware of it as few take the trouble to read the certificate and in the UK it does not appear to be the norm to provide all owners with a copy anyway. (On the Continent it is vital to have one in order to be able to register a vehicle as without it their equivalent of a V5c can't be issued). In case of dispute should one run into a roadside check that only has a look at the VIN plate, the powers-that-be would be able to access the contents of the CofC, so there's no need to carry it along with you as proof.
It may be a final word from Mitsubishi, but by definition kerbweight cannot be shown in an owner's manual unless every car that comes off the line weighs exactly to same, regardless of spec, which is hardly the going to be the case. If it's not linked to a particular chassis number it can't really be kerbweight.
I know. This figure was reached from the Registration number so they are looking at our particular car. It’s ridiculous. I’m sticking to the figures I have gained from 2 separate weighbridges and happy to work from them.
What’s annoying is, our first van choice was based around this ”kerbweight” when in actual fact, we had much more choice than we thought.
As I mentioned before, go to the weighbridge with your tug in the lightest cofiguration that "you" would tow. ie maybe 1/4 tank of fuel, and with just tourself in the tug get that weight and use that as a start weight.
My tug weight could vary by almost 500 kg , towing from almost empty fuel and just myself in it, to full fuel, wife, dogs, awning Cadac and kitted out for a 6 weeks tour of Europe. Dragging a 1645 kg caravan.
My tug weight could vary by almost 500 kg , towing from almost empty fuel and just myself in it, to full fuel, wife, dogs, awning Cadac and kitted out for a 6 weeks tour of Europe. Dragging a 1645 kg caravan.
If you look back through this thread, you’ll see that’s precisely what I have done at 2 separate weighbridges and the measurements are pretty much bang on. One with 3/4 tank and one with 1/4 tank. They come off at 1860kg and 1830kg respectively. So I’m confident with that figure.
Perhaps I am missing somthing here, so please correct me if I am wrong.
The OP is trying to determine the outfits mass in order to tow safely and within the law. That, of course is commendable. Getting the cars has shown to be variable. Arguably, using a weigh bridge should be most accurate.
In the unlikely event of being stopped for a random check. What will the police go by?
John
The OP is trying to determine the outfits mass in order to tow safely and within the law. That, of course is commendable. Getting the cars has shown to be variable. Arguably, using a weigh bridge should be most accurate.
In the unlikely event of being stopped for a random check. What will the police go by?
John
Surely if stopped for a check it’s DVSA that carry out the weighing. In my case the police motorcycle rider just came alongside and waved me to follow to the weighbridge. Must have been a Byelorussian cop.
But the weighbridge will be the guiding figure checked against the cars VIN plate weight limits.
I intend to make 2 more weighbridge trips. One on my way back from collecting the van from the dealer with both car and van at lowest weights and then one with all equipment, family and dogs in as though going away with it.
As far as road side checks are concerned, they will not care what the the kerbweight is, they are principally looking for unsafe vehicles or overloads.
An overload by definition means an actual measured load that exceeds a stated limit. it cannot be ascertained by simply looking a data plates or specifications it has to include a measured value.
The Kerbweight has very little relevance except for the owner who might want to work out what his theoretical loading margin is, but as this and other threads have established is fraught with difficulties, not only because the kerbweight supplied by most manufacturers is only representative of type approval model, and usually differs to the real kerbweight of the car on your drive. This makes a mockery of the calculated loading margin.
The arbiter from a legal perspective are the cars data plate weight limit values which must no be exceeded. - Simples.
An overload by definition means an actual measured load that exceeds a stated limit. it cannot be ascertained by simply looking a data plates or specifications it has to include a measured value.
The Kerbweight has very little relevance except for the owner who might want to work out what his theoretical loading margin is, but as this and other threads have established is fraught with difficulties, not only because the kerbweight supplied by most manufacturers is only representative of type approval model, and usually differs to the real kerbweight of the car on your drive. This makes a mockery of the calculated loading margin.
The arbiter from a legal perspective are the cars data plate weight limit values which must no be exceeded. - Simples.
I’m happy that I have explored all avenues with this now and that I have reliable measurements to work from (which informed our choice of van last weekend)
Now, when it arrives I can get empty and loaded weights from it with a fair degree of accuracy and then drive confidently knowing I am within all safe limits both for towing and keeping my weight distribution and axle limits under control.
In the vast majority of cases that is true, yes, but my BMW, for example, has a different max. allowable GVW depending on whether it is towing (2510kg) or not (2410kg). Of course, the weight plate only shows the lower (solo) limit. Because there are no provisions for two values on the plate, the other one can only be found in the type approval Certificate of Conformity. I doubt whether many owners are aware of this, though.
I certainly wasn't.
Weren't Vauxhalls the same? The more payload in the car, the less you could tow or vice versa?
Some Citroen’s had that restriction too.
That’s similar but not quite the same. In the case of the Vauxhalls (Citroens and a few others were the same) the towload limit was higher than the gross train weight minus gross vehicle weight. In the case of my BMW, however, the towload limit remains unchanged, but the car can be a bit heavier when towing.
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