Vehicle weight

[judsley]

Apologies for the stupid question but is "gross vehicle weight' the same as kerb weight and is "gross train weight" the same as maximum tow limit of the car?
I have a '57 plate Ford Focus Titanium Estate and in the hand book it has the weights as 1950kgs and 3450kgs respectively. I'm trying to work out what size of caravan I can tow bearing in mind the 85% rule.
Maths was never my strong point!
Thanks for any help.
Jon

 

[hortimech]

Hi, "gross vehicle weight" is the maximum the vehicle can carry, ie fully laden; "gross train weight" is the maximum weight of the fully laden vehicle plus the maximum weight of the fully laden caravan.
Or, to put it another way, max caravan weight = gross train weight, 3450kg - gross vehicle weight, 1950kgs = 1500kgs. So you can tow a caravan that weighs no more than 1500kgs when fully laden.
This is less than 85% of the gross vehicle weight.

 

[Lutz]

No, gross vehicle weight is kerbweight plus maximum payload. Gross train weight is the maximum permissible total weight of the outfit, i.e. car plus caravan. Subtract one from the other and you have the maximum permissible towload which is a legal limit.
The kerbweight (or actually the Mass in Service) is documented in Section 4 of the V5c certificate.
It would be better to refer the 85% formula as a recommendation than as a rule. A rule always sounds as though it is something that is cast in stone and must not be exceeded, whatever. It does not, however, have any legal significance.

Hi, "gross vehicle weight" is the
maximum the vehicle can carry, ie fully laden; "gross train weight" is
the maximum weight of the fully laden vehicle plus the maximum weight of
the fully laden caravan.
Or, to put it another way, max caravan
weight = gross train weight, 3450kg - gross vehicle weight, 1950kgs =
1500kgs. So you can tow a caravan that weighs no more than 1500kgs when
fully laden.
This is less than 85% of the gross vehicle weight.

Hortimech's reply is a bit misleading. The 85% is based on the car's kerbweight (Mass in Service), not its gross vehicle weight.
Besides, using his figures, the 1500kg is NOT the maximum weight that the car may tow, but the maximum allowable axle load of the caravan. The actual maximum weight of the caravan would be 1500kg plus the noseweight.

 

[judsley]

Thanks for the replies. I hadn't thought of looking at the V5c document to get the info I asked about. That being said I didn't know mass in service was the kerbweight (which is 1426kgs)
So, based on the above can I take it i'd be ok to to a Bailey Senator Indiana which has an unladen weight of 1264kgs and a MTPLM of 1500kgs? (I did say maths was never my strong point!).
Thanks once again.
Jon

 

[Lutz]

Yes, you can legally, but you wouldn't be within the 85% recommendation. If the Mass in Service is 1426kg, then, to keep within the 85% recommendation, the MTPLM of the caravan shouldn't exceed 1212kg.

 

[judsley]

Lutz
You're a star, thanks.

 

[hortimech]

Hortimech's reply is a bit misleading. The 85% is based on the car's kerbweight (Mass in Service), not its gross vehicle weight.
Besides, using his figures, the 1500kg is NOT the maximum weight that the car may tow, but the maximum allowable axle load of the caravan. The actual maximum weight of the caravan would be 1500kg plus the noseweight.

the 85% rule is just that a rule and has no basis in law. What I quoted was the law, if you subtract the gross vehicle weight from the gross train weight, you get the maximum weight of the caravan. If you move some of the weight of the caravan (nose weight) to the vehicle you must subtract this from the gross vehicle weight, you cannot exceed the gross train weight. So if you take the nose weight to 80kgs, then yes the caravan could be 1580kgs, but the vehicles gross weight would have to be reduced to 1870kgs.

But, having said all that, I based my figures on what VOSA quotes, trailer weight = gross train weight - gross vehicle weight, so I think I will stick to what VOSA says.

 

[Lutz]

What I quoted was the law, if you subtract the gross vehicle weight from the gross train weight, you get the maximum weight of the caravan. If you move some of the weight of the caravan (nose weight) to the vehicle you must subtract this from the gross vehicle weight, you cannot exceed the gross train weight. So if you take the nose weight to 80kgs, then yes the caravan could be 1580kgs, but the vehicles gross weight would have to be reduced to 1870kgs.

But, having said all that, I based my figures on what VOSA quotes, trailer weight = gross train weight - gross vehicle weight, so I think I will stick to what VOSA says.

You have not quoted the law.
If you subtract the gross vehicle weight from the gross train weight you do NOT get the maximum weight of the caravan. You will get its maximum axle load. Gross train weight is NOT the sum of gross vehicle weight of the car and the total weight of the caravan, including its noseweight. If the MTPLM of the caravan is 1580kg and its noseweight 80kg, the gross vehicle weight with the caravan attached will continue to be 1950kg and the gross train weight will also continue to be 3450kg.
Gross train weight is defined as the SUM OF ALL AXLE LOADS. The 1870kg that you have quoted will be the maximum allowable weight of the towing vehicle when measured on its own, without the caravan attached, but that is not its gross vehicle weight.
I'm afraid you have either misunderstood what VOSA told you or someone got their facts wrong.

 

[ProfJohnL]

Hello Hortimech,

The way you calculated judsley's ratio is not consistent with the traditional method, so your statement "This is less than 85% of the gross vehicle weight." is misleading as you were comparing different criteria to those traditionally used.

The traditional method is MTPLM/MIS x 100%

Using judsley figures calculates out to

1500(MTPLM)/1426(MIS)= 1.05 or 105%

Whilst this is not illegal for the vehicle, it is above the 85% guideline for new towers and above the 100% top guide suggested by the caravan industry.

With regards to the maximum train weight, Your method of GTW = GVW + MTPLM is perfectly safe, but not quite correct, as it fails to take full account of the nose weight.

The car manufacture quotes the trailed weight limit for the car, which is in fact the load on the trailers axle not its MTPLM. The nose load is therefore in addition to the axle load and is carried not trailed by the car. Consequently the nose load has to be accounted as part of the cars load.

Lutz is quite correct when he suggests that Judsley's caravan could have an MTPLM of 1500 + Nose weight. And I understand your concerns about the cars load, but where you are have misunderstood the situation is the difference in in definition of GVW (Which is also MAM) and "Vehicles Weight".

The GVW is the upper weight limit and not a measurement, so it is true to say the VW must not exceed the GVW. If you had a car laden to its GVW, and you then attached a trailer the nose weight would cause the car to be over loaded, so to accommodate the trailers noseweight you would have to shed some other part of the cars content to bring it down to under the GVW limit.

 

[Surfer]

Maybe I am wrong, but I think originally many years ago kerbweight was the weight of the vehicle when it left the factory. Later kerbweight included a driver, fluids plus some luggage and is now known as MIRO or MAS in the EU to avoid confusion.

 

[colin-yorkshire1]

hi guys,
while all the maths is interesting stuff, sometimes a step back is required for a look at the bigger picture.

the calculations above may be all sound in principal, but the first look should be if the vehicle manufacturer has place a maximum trailer weight on the vehicle some do and it may be a lot less than the maths allow. the critera for the calulations would then change,
also the OP has to think before buying a van to tow, what and where he is likely to tow it considering all the senarios he may come across.
for instance down the line he may plan a trip across europe for a month taking in a voyage across the alps fully loaded would that be wise towing a near on 1600kg van with a focus for a couple of thousand miles
it may well be? but all I am saying is sometimes the maths don't add up.

 

[Lutz]

Maybe I am wrong, but I think originally many years ago kerbweight was the weight of the vehicle when it left the factory. Later kerbweight included a driver, fluids plus some luggage and is now known as MIRO or MAS in the EU to avoid confusion.

Kerbweight is the weight of the unladen vehicle with all fluids and a full fuel tank, but no driver.
MAS is not a recognised abbreviation. MIRO (also known as Mass in Service in the V5c certificate) is the same except with the fuel tank only 90% full and it includes a 75kg allowance for the driver and sundry items.
Hence, kerbweight and MIRO are not quite the same thing. Kerbweight is not documented anywhere, MIRO is.

the
calculations above may be all sound in principal, but the first look
should be if the vehicle manufacturer has place a maximum trailer weight
on the vehicle some do and it may be a lot less than the maths allow.
the critera for the calulations would then change,

But the calculations are based on the details shown on the VIN plate and V5c certificate, respectively, and all these are figures supplied and specified by the manufacturer.

 

[hortimech]

You have not quoted the law.
If you subtract the gross vehicle weight from the gross train weight you do NOT get the maximum weight of the caravan. You will get its maximum axle load. Gross train weight is NOT the sum of gross vehicle weight of the car and the total weight of the caravan, including its noseweight. If the MTPLM of the caravan is 1580kg and its noseweight 80kg, the gross vehicle weight with the caravan attached will continue to be 1950kg and the gross train weight will also continue to be 3450kg.
Gross train weight is defined as the SUM OF ALL AXLE LOADS. The 1870kg that you have quoted will be the maximum allowable weight of the towing vehicle when measured on its own, without the caravan attached, but that is not its gross vehicle weight.
I'm afraid you have either misunderstood what VOSA told you or someone got their facts wrong.

You are now splitting hairs, axle loads and weights are, as far as I am concerned, the same thing. The GVW comes from adding the maximum weight that axle 1 and axle 2 will carry, in this case 1950kgs. GTW is trailer/caravan weight plus GVW, so the maximum the trailer/caravan can weigh (or as you put it, axle load) is 3450kgs (GTW) minus 1950kgs (GVW) which equals 1500kgs.
Now as was rightly said, some of the weight of the trailer/caravan is transferred to the vehicle via nose weight, but you cannot exceed the GTW.
If you get weighed by VOSA, they weigh the vehicle axles and then the caravan axle and if any of these measurements exceed the allowed limits, you are in trouble.

If you still don't believe what I am saying, go here: http://www.dft.gov.uk/vosa/repository/Quick%20guide%20to%20towing%20small%20trailers.pdf

The maths is a bit suspect and I have sent them an email about it, but it explains fully what I have tried to explain. To be legal, forget MTPLM etc, they have no basis in law, all VOSA cares about is axle weights. To VOSA a caravan is a fancy trailer.

 

[colin-yorkshire1]

the
calculations above may be all sound in principal, but the first look
should be if the vehicle manufacturer has place a maximum trailer weight
on the vehicle some do and it may be a lot less than the maths allow.
the critera for the calulations would then change,

But the calculations are based on the details shown on the VIN plate and V5c certificate, respectively, and all these are figures supplied and specified by the manufacturer.

hi Lutz, nowhere on the Meriva does the VIN plate or V5c give the maximum trailer weight, only the max axel weights and GVW and GTW deducting the GVW from the GTW would give a max tow weight of 1225kg + 50kg noseweight = 1275kg however it is not untill reading the handbook that the manufacturer states the maximum trailer weight is 1200kg for that model. similary some Rover models have the maximum tow weight pegged at 1000kg even though doing the maths gives a tow weight of 1375 kg.
I would suggest that this lower figure is the one to use, instead of relying on a calculator for a figure,
I don't know what Ford recommmend for their models but the fact remains would you tow a 1600kg van over the Alps with a Focus.

 

[Lutz]

You are now splitting hairs, axle loads and weights are, as far as I am concerned, the same thing (No, they are not). The GVW comes from adding the maximum weight that axle 1 and axle 2 will carry, in this case 1950kgs (correct). GTW is trailer/caravan weight plus GVW (no it isn't), so the maximum the trailer/caravan can weigh (or as you put it, axle load) is 3450kgs (GTW) minus 1950kgs (GVW) which equals 1500kgs (again, 1500kg is the maximum axle load, which is NOT the same as its total weight).
Now as was rightly said, some of the weight of the trailer/caravan is transferred to the vehicle via nose weight, but you cannot exceed the GTW (correct).
If you get weighed by VOSA, they weigh the vehicle axles and then the caravan axle and if any of these measurements exceed the allowed limits, you are in trouble (correct. I see you now agree that they measure the caravan axle load, not its weight).

If you still don't believe what I am saying, go here: http://www.dft.gov.uk/vosa/repository/Quick%20guide%20to%20towing%20small%20trailers.pdf
The 'VOSA quick guide to towing small trailers' in no way contradicts anything that I have written. The 'max to trailer design' referred to in their sketch clearly refers to the trailer's axle load, not its weight.
The maths is a bit suspect and I have sent them an email about it, but it explains fully what I have tried to explain. To be legal, forget MTPLM etc, they have no basis in law, all VOSA cares about is axle weights. To VOSA a caravan is a fancy trailer.
Not exceeding the MTPLM is just as important as not exceeding the GVW and GTW limits.

 

[ProfJohnL]

I do regret the subject of weights and loads always seems to produce such diversity of opinion, it goes to show the subject is complex and should not be over simplified. Despite its apparent complexity, it does have a logical basis, so taking careful small steps through the mire of information and principals - with a little well founded advice a safe course can be navigated.

It is really unfortunate that so many people searching for information on a subject - such as vehicle weights etc, and they find a document but don't read it properly or understand where it sits in relation to the regulations behind it.

Some basic clues: -If a document says its a guide, it means it's not the complete definitive statement on the subject.

If it makes specific references to other legislative documents as sources, then the document in view is not definitive.

Especially with guides to legal matters often its what's not written that as important as what is written.

Specifically in relation to this Document, I suspect that at least two contributors have read it and come to the inaccurate conclusion that MTPLM is not specifically mentioned so its not relevant. - definitely not true.

I draw you attention to the first sentence on the second page
"The trailer may also display similar information showing the capacity of the axles and the maximum weight it can carry."

The focus of the sentence is 'the trailer' it mentions the capacity of the axles but it most importantly goes on to mention the 'maximum' weight -"it" (being the trailer) can carry. That sentence clearly shows that the axle capacity is not the only criteria VOSA must look at, they would consult the trailer manufacturers specification to see if the bodywork has a lower weight limit than the axles on which it's fixed.

It certainly is not splitting hairs to consider the differences between loads, weights, and masses etc if the relevant legislation makes the distinction between them, they do so for a reason.

 

[Surfer]

As stated I think we can all agree that the term MTPLM has no relevance in law and you cannot be prosecuted for exceeding the MTPLM for a trailer despite the plate being on the trailer. The plate is not a regulation type plate. However you can be prosecuted for exceeding the load rating on the tailer tyres or the axle weight rating.
Having said that, it is common sense and good practice not to exceed the MTPLM that the manufacturer has stated on the plate and also saves you a lot of hassle.

 

[Lutz]

hi Lutz, nowhere on the Meriva does the VIN plate or V5c give the maximum trailer weight, only the max axel weights and GVW and GTW deducting the GVW from the GTW would give a max tow weight of 1225kg + 50kg noseweight = 1275kg however it is not untill reading the handbook that the manufacturer states the maximum trailer weight is 1200kg for that model. similary some Rover models have the maximum tow weight pegged at 1000kg even though doing the maths gives a tow weight of 1375 kg.
I would suggest that this lower figure is the one to use, instead of relying on a calculator for a figure,
I don't know what Ford recommmend for their models but the fact remains would you tow a 1600kg van over the Alps with a Focus.

Manufacturers don't quote maximum trailer weights but maximum braked trailer or towed weights. The brakes on the trailer act on its axle only, not its total weight. It's the job of the car's brakes to act on the total weight of the car, including the noseweight which the car is carrying, not towing. Therefore, the noseweight part of the trailer's total weight is NOT included in 'braked trailer weight'.

As stated I think we can all agree that the
term MTPLM has no relevance in law and you cannot be prosecuted for
exceeding the MTPLM for a trailer despite the plate being on the
trailer. The plate is not a regulation type plate.

No, I am afraid we cannot agree on that, at least not in the case of those trailers of recent manufacture which are subject to whole vehicle type approval and where the details on the plate are covered by the legal requirements stipulated in Construction and Use Regulations.

 

[ProfJohnL]

As stated I think we can all agree that the term MTPLM has no relevance in law and you cannot be prosecuted for exceeding the MTPLM for a trailer despite the plate being on the trailer. The plate is not a regulation type plate. However you can be prosecuted for exceeding the load rating on the tailer tyres or the axle weight rating.

Hello Surfer,

You are mistaken - we cannot all agree on your dismissal of MTPLM having legal relevance.

You have made the same assertion several times now and each time I have searched for any official document, or regulation that excludes MTPLM with no hint found.

But I do find it rather telling that several contributors other than me, have concurred with my view, and also your piece printed in PC mag on the subject also received an editorial comment about the unsoundness of your contention.

I will be happy to support your contention, but I do need verifiable proof of the fact, so please will you give the source of your information so we can all benefit from the increased weight we can now tow.

 

[colin-yorkshire1]

hi Lutz, nowhere on the Meriva does the VIN plate or V5c give the maximum trailer weight, only the max axel weights and GVW and GTW deducting the GVW from the GTW would give a max tow weight of 1225kg + 50kg noseweight = 1275kg however it is not untill reading the handbook that the manufacturer states the maximum trailer weight is 1200kg for that model. similary some Rover models have the maximum tow weight pegged at 1000kg even though doing the maths gives a tow weight of 1375 kg.
I would suggest that this lower figure is the one to use, instead of relying on a calculator for a figure,
I don't know what Ford recommmend for their models but the fact remains would you tow a 1600kg van over the Alps with a Focus.

Manufacturers don't quote maximum trailer weights but maximum braked trailer or towed weights. The brakes on the trailer act on its axle only, not its total weight. It's the job of the car's brakes to act on the total weight of the car, including the noseweight which the car is carrying, not towing. Therefore, the noseweight part of the trailer's total weight is NOT included in 'braked trailer weight'.

Well now even I'm confused

and I thought I was well savvy and up on all the weight issues,
I just don't see how just doing the maths would square the circle. we all know the issue is complex but things just don't add up.
take the Meriva for instance there are no weights on the VC5 as it is a 2004 model, so the only reference point is the VIN plate, this reads, 1.1935kg, 2. 3160kg. 3. 1045kg. 4. 950kg.now given that
3.is front axel load and
4.is rear axel load
adding the two together should give the gross vehicle weight in 1. ie 1935kg but it does not because 3. and 4. added together is 1995kg so there is a difference of 60kg, now the maximum noseweight of the Meriva is 50kg, this cannot be added to the rear axel weight although this is where it goes, because you would exeed the maximum of 1.1935kg the gross vehicle weight if you deduct it from 4. this lowers the max rear axel weight from 950kg to 900kg assuming the car was fully loaded,
if weighed by VOSA and the front axel weight was 1040kg and in limits and the rear axel inc noseweight was 945kg again within limits you would still be overweight by 50 kg ie 1040+945= 1985kg.as the GVW is plated at 1935kg.

this leads to the conclusion that the assumtion as stated above that the figure for 3. and 4. added together makes 1. is WRONG.
if the front axel is fully loaded the rear axel cannot be and has to be reduced or visa versa adding the noseweight to the rear axel must reduce the gross vehicle weight by a factor of x2 ie 50kg of noseweight + 50kg difference between axels =100kg.
before hitching up the van the gross vehicle weight or GVW cannot be any more than 100kg underweight or you would be overweight by the time the van was on the back.

secondly the previously stated assumtion that 1. GVW deducted from 2. GTW gives a accurate maximum trailer weight it DOES NOT. and also must be wrong, because some vehicle manufacturers give a max trailer weight well below the plated equivelent. again in the Meriva the GTW or 2. is 3160kg while the GVW in 1. is 1935kg, 2 minus 1 = 1225kg given that this is the trailed weight (minus noseweight) as stated by Lutz, would mean a van with a MTPLM of 1275kg could be towed ie 1225kg +50kg noseweight.
but the handbook clearly states the "max braked tailer weight" is 1200kg for my model even if you add the nose weight (allthough there is no mention of it) the plated weight would be 25kg over,

but thats not the whole picture because using the plate to make calculations adding 3.and 4. and and the calculated tow maximum 1275kg deduductiing from 2. giives a GTW of 3220kg or 60kg over the plated GVW stated in 2.
but deducting the max trailer weight of 1200kg from the plated GTW, in 2. gives a figure of 1960kg or 25kg over the plated GVW in 1.

which ever way the weights are calculated via the VIN plate the figures just don't add up

.

 

[TrevorM]

Colin, I think it may be a mistake to expect the numbers to 'add up.' I do not think anyone is saying you can utilise the maximum front and rear axle weights st the same time. Therefore if you are running the maximum front axle load then the rear can not be at the maximum if you are at the GVW, and vice-versa.
Eg. assume GVW = 2000, front limit = 1100, rear limit = 1050. If actual front axle weight = 1100 and total weight is at 2000, then rear weight must be less than 1050 (and will actually be 900.) Conversely, you could have front at 950, total weight at 2000 and rear at 1050.
Just my tuppence worth on a widely confusing topic.
Enjoy your holidays,
Trevor M
PS: having re-read your post I think you had already come to this conclusion!

 

[Lutz]

As Trevor says, the maximum allowable front axle load and that of the rear axle need not necessarily add up to max. GVW. This is to give the owner leeway in how the payload is distributed front to rear. A bit further forward will increase the front axle load, a bit further to the back increases the rear axle load, although the total vehicle weight can remain the same.
Noseweight doesn't enter into the equation as it is always included in the 950kg max.rear axle load.
Having said that, there certainly seems to be a disconnect between the details shown on the VIN plate and those in the handbook. Although, strictly speaking, the figures on the VIN plate are those that count as they have the same standing as a document, the towload quoted in the handbook agrees with the vehicle type approval data, of which I have a copy. It would be fairly easy to find an explanation if the max. towload were greater than the difference between GVW and GTW, but in this case it's the other way round and that doesn't make sense to me.

 

[colin-yorkshire1]

Having said that, there certainly seems to be a disconnect between the details shown on the VIN plate and those in the handbook. Although, strictly speaking, the figures on the VIN plate are those that count as they have the same standing as a document, the towload quoted in the handbook agrees with the vehicle type approval data, of which I have a copy. It would be fairly easy to find an explanation if the max. towload were greater than the difference between GVW and GTW, but in this case it's the other way round and that doesn't make sense to me.

no Lutz and it doesn't make sense to me either?? the type approval as you say agrees with the handbook ie. 1200kg assuming the nose weight is 50kg also in the type approval this could concievably be streached to 1250kg. but not 1275kg as the VIN plate indicates, mind you as the MTPLM of our van is less than 1100kg it is not going to cause any hardship but the anomaly is still there.
Also I do understand the dynamics of axel loads and the distribution of weight (like roof rack for example) and the fact that as the vans noseweight is carried by the rear axel it must allways be 50kg less than the plated weight before the van is attached. and as such will affect the vehicle loading,

however the assumtion of the statment that, "The GVW comes from adding the maximum weight that axle 1 and axle 2 will carry, in this case 1950kgs (correct)". is indeed flawed from a mathematical point of view, as is the assumtion that the GTW minus GVW would give the true maximum trailer load. the Meriva clearly demonstrates this is not so. as would the same calculations done on a Rover or Renault.
In my view the only true method of determining the legal requirments of any outfit is (do the maths by all means) BUT then go and get the whole thing weighed on a weigbridge,.

 

[Lutz]

Which engine and transmission combination has your Meriva got? There are a couple of variants with a 1300kg towload limit. The 1.7CDTi with a 6 speed manual box, which I once had, is one of them. In those cases one could explain why GVW and towload limit possibly don't add up to the stated GTW.

 

[colin-yorkshire1]

Which engine and transmission combination has your Meriva got? There are a couple of variants with a 1300kg towload limit. The 1.7CDTi with a 6 speed manual box, which I once had, is one of them. In those cases one could explain why GVW and towload limit possibly don't add up to the stated GTW.

hi, Lutz, it's a 2004 1.7CDTi with 5speed manual box, (with A/C) Enjoy model,