Kerbweight advice please

DavidN

I have three weight figures for my car that may be classed as Kerbweight, which should I use for calculating the 85% recommended caravan weight. 

I have a manufacturer's kerbweight of 1578kg

A V5 reg document Mass in Service figure of 1652kg

A weighbridge printout of 1820kg.

There seems to be little knowledge in the car and caravan dealers that I have approached of the meaning of kerbweight, even the car manufacturer said to ignore their figure and use the weighbridge figure.

I find all car dealers I have asked refer to the max towing weight and do not appreciate the importance of the car kerbweight to caravan max weight ratio or that the max towing weight is derived from an hill start test.

Surely something as important as this to caravaners should be standardised and with a clear definition of kerbweight.

Thanks 

Dave

Lutz

The reason why you are getting conflicting information is because there is no legal definition of kerbweight. Industry convention says that it is the ex-works weight of the vehicle in running order with a full tank and no driver, but current legislation doesn't use the term kerbweight. Instead, the term is 'mass in running order' and that is defined differently. However, because the term kerbweight is so ingrained in general use, some sources use the term kerbweight when they actually mean mass in running order. That all adds to the confusion.

The reason why mass in running order, or mass in service as the V5c calls it, is so much less than the weighbridge print out is because mass in running order is for a vehicle of the same type but with a minimum of factory fitted options that are standard for the market in which the vehicle is sold. It does not therefore reflect any upgrading options that may be fitted to the specific vehicle in question. The lawmakers have since appreciated this disconnect and with the implementation of EU directive 1230/2012/EC they have introduced a further new definition, that of 'actual mass of the vehicle'. Under item 13.2, this may be documented in the Certificate of Conformity that was issued with the vehicle, but it will not be found in the V5c.

Settermum

This is a highly frustrating subject. I've just changed my car too and although the CCmatching service gives a "good" match to my outfit, the weight they used for my car is not the same as it says on my V5. All the confusion.regarding "kerb weight" "Mass
in service" whether it includes the driver and/or fuel, is it any wonder my head hurts. You would think that the Caravan Club would have an absolute definition that we could all rely upon without all this annoying confusion.

Lutz

Fact is that every car weighs differently. Fluctuations of up to 150kg can be expected even for the same model. That's why you will never get anything else but a rough guide, no matter which source of information you use.

It would help if the clubs stop using the term kerbweight as it always leads to confusion so long as UK legislation doesn't define it. And there's no point in the clubs going it alone in defining kerbweight if the manufacturers that provide the information aren't held to the same definition.

Settermum

It seems to me that the harder you try to do things properly, legally and safely, the more confused you get. There must be hundreds if not thousands of people carananning in blissful ignorance of all this "stuff". 

ChrisRogers

In my Skoda handbook technical section there is no referance to kerbweight, only
'unloaded weight ready for work'
which is 1,495kg and that is on the V5C for mass in service.

Lutz

In my Skoda handbook technical section there is no referance to kerbweight, only 'unloaded weight ready for work'which is 1,495kg and that is on the V5C for mass in service.

Now that's a term that I've never heard before and it's not even grammatically correct. If anything it should be called 'unladen weight', but that is defined in UK legislation as the weight with no payload and an empty tank, which corresponds neither to kerbweight (full tank) nor mass in service (tank 90% full). Ready for work? What work? Sounds like a very poor translation to me.

I wish manufacturers would stick to terms that are well defined and use them in that way, too. Everything else just adds to the confusion.

nelliethehooker

Lutz, which of the figures given would you suggest the OP uses to calculate the 85% level?

Lutz

Lutz, which of the figures given would you suggest the OP uses to calculate the 85% level?

In view of the fact that any calculation of weight ratio has its shortcomings because it hardly ever reflects actual conditions, I have my reservations about the whole concept of weight ratios. However, if the OP feels compelled to work a weight ratio out
I would always use the highest figure even though that would, strictly speaking, not be reconcilable with either the definition of kerbweight or of mass in service, but at least it comes closest to a worst case scenario in a real live situation.

cyberyacht

Surely you mean the "lowest" figure?

Lutz

No, I mean the highest as the lowest figure is normally far too unrealistic to represent anything like actual conditions. The lowest generally takes only a very basic model without any options into account. Therefore, only the highest figure will give one
anything like a representative value and even then it should be borne in mind that it is still a worst case scenario with a virtually empty car with just the driver pulling a fully laden caravan.

DSB

All this is a good reason for me to stick with my Discovery 3, I think.  There's a good chance it will be able to pull most caravans without being over concerned with kerb weights etc.

David 

EmilysDad

All this is a good reason to stick with my Discovery 3, I think.  There's a good chance it will be able to pull most caravans.

David 

but weight ratios are more to do with stopping it 

Lutz

but weight ratios are more to do with stopping it 

Not really. The caravan should be quite capable of stopping itself, at least in the dry. It's more a matter of how the outfit handles when subjected to unforeseen outside influences like a bout of crosswind or the need for sudden evasive action

EmilysDad

but weight ratios are more to do with stopping it 

Not really. The caravan should be quite capable of stopping itself, at least in the dry. It's more a matter of how the outfit handles when subjected to unforeseen outside influences like a bout of crosswind or the need for sudden evasive action

Lighten up Lutz - I know ...... 

nelliethehooker

Thanks, Lutz. Hope that helps DavidN with his query.

DavidN

Thanks, Lutz. Hope that helps DavidN with his query.

I feel  inclined to go with the weighbridge figure???

Dave

catherinef

I'm taking our Q3 this morning to be weighed on our weigh to collect the caravan from the dealer.  £12 per weigh apparently.  Next Tuesday I'll probably then go and weigh the caravan on the way back to the storage compound.

catherinef

Just been on the weighbridge.  The Q3 weighed 1740 kgs Fully Fuelled.  That was without a driver.  The handbook for a car with no options fuel  or driver is 1620 kgs.   The Mass in Service weight is 1700 kgs.  

Lutz

That all sounds very plausible. The difference between the weighbridge figure and that of mass in service is about what one would expect, as is the handbook figure if it's without options, fuel or driver.

Toro

The mass in service weight quoted on the V5 would not  include the towbar. I go by the quoted mass in sevice weight as i believe this is the weight recognised as the accepted figure by the DOT

Lutz

The mass in service weight quoted on the V5 would not  include the towbar. I go by the quoted mass in sevice weight as i believe this is the weight recognised as the accepted figure by the DOT

As the weight ratio has no relevance in legislation it seems a little pointless in using a figure that can be quite far off the mark, thereby giving an exaggerated result. Unless the actual weight is quoted in the CoC, weighbridge measurement of the car
without any payload except the driver is probably the most appropriate and perhaps the sources that make the weight ratio recommendation should revise their advice accordingly.

redface

Oh heck, i'll just carry on caravanning in complete ignorance and trust to my own judgement. Its all way too far above my head!