Kerbweight

Lutz
Lutz Forum Participant Posts: 1,564 ✭✭✭✭
edited December 2020 in Caravans #1

In a since locked thread about outfit matching services reference was made to kerbweight being a variable. I don't want to get into a lengthy discussion regarding other statements made in the topic (I presume that the thread was locked due to the likelihood of it becoming a long drawn out matter) but I would just like to quote the definition of kerbweight and leave it at that. Perhaps things will be a bit clearer that it is not variable:

The Road Vehicles (Construction & Use) Regulations 1986 define kerbweight as follows:

the weight of a vehicle when it carries—
     (a) in the case of a motor vehicle,
          (i) no person; and
          (ii) a full supply of fuel in its tank, an adequate supply of other liquids incidental to its propulsion and no load other than the loose tools and equipment with which it is normally equipped;
     (b) in the case of a trailer, no person and is otherwise unladen.

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Comments

  • lornalou1
    lornalou1 Forum Participant Posts: 2,169
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    edited December 2020 #2

    Lutz. People will still ask the question for years to come even when it's so simple.  

  • Fozzie
    Fozzie Club Member Posts: 550
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    edited December 2020 #3

    A: Kerb weight is the weight of a car with all fluids (coolant, engine oil, brake fluid) plus a full tank of fuel and a driver weighing 75kg. It's measured when new cars are put forward for UNECE (United Nations Economic Commission for Europe) type approval by their respective manufacturers.

     

    Lutz,much as I will bow to your superior knowledge on this subject,you can see why people find this so so confusing.I had always thought the kerbweight included 75kg for the driver.

  • dawlishpete
    dawlishpete Forum Participant Posts: 16
    edited December 2020 #4

    Well thats interesting....

    heres my volvo from the volvo website. So is the driver a slim lady of 60kg or a big fat git at 130kg?

    Max. gross vehicle weight, etc. can be read on a label in the car.
    Kerb weight includes the driver, the fuel tank 90% full and all fluids.

    The weight of passengers and accessories, and towball load (when a trailer is hitched) influence the load capacity and are not included in the kerb weight.

    Permitted max. load = Gross vehicle weight - Kerb weight.

  • EmilysDad
    EmilysDad Forum Participant Posts: 8,973
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    edited December 2020 #5

    I was at school when I was only 75kg ..... 🙄

  • dawlishpete
    dawlishpete Forum Participant Posts: 16
    edited December 2020 #6

    From the Gov.uk website, makes no mention of kerbweight which i believe is a leftover of ancient towers folklore...

    Towing weight and width limits
    Most cars have a maximum weight they can tow. It’s usually listed in the handbook or specification sheet.

    Alternatively the vehicle’s ‘gross train weight’ may be listed on the vehicle identification number (VIN) plate on the car. This is normally under the bonnet or inside the driver’s door.

    The gross train weight is the weight of the fully-loaded car plus fully-loaded trailer and must not be exceeded.
    If your VIN plate doesn’t list a train weight, you should not use your vehicle for towing.

    Width and length
    The maximum trailer width for any towing vehicle is 2.55 metres.

    The maximum length for a trailer towed by a vehicle weighing up to 3,500kg is 7 metres. This length does not include the A-frame.

  • Lutz
    Lutz Forum Participant Posts: 1,564 ✭✭✭✭
    edited December 2020 #7

    What you are stating is a cross between the definition of mass in running order (also known as mass in service in the V5c) and and that of kerbweight. UNECE type approval makes no mention of kerbweight, only of mass in running order and that does include 75kg for the driver, but only a 90% full fuel tank. Kerbweight is a UK thing and only defined in UK legislation which I quoted above.

  • dawlishpete
    dawlishpete Forum Participant Posts: 16
    edited December 2020 #8

    It seems the latest version of the sites manual has another view...

  • Lutz
    Lutz Forum Participant Posts: 1,564 ✭✭✭✭
    edited December 2020 #9

    The information that you have provided, dawlishpete, would indicate that car manufacturers are free to interpret kerbweight as they wish. This would conflict with UK legislation.

    What is true, however, is that car manufacturers are under no legal obligation to publish kerbweights.

  • Rayrowe35
    Rayrowe35 Forum Participant Posts: 112
    edited January 2021 #10

    Maximum train weight and maximum towing weight are issued by the manufacturer and usually based on the ability of the fully loaded towing vehicle and trailer being able to start on a 1 in 10 gradient without compromising the integrity of the vehicle. The trailer may be a caravan or a horse box or some other undefined trailer. The maximum towing weight does not imply that the outfit will be stable. Indeed, no manufacturer could make this claim on a trailer not of their manufacture. 
    It would be better if the caravan industry adopted the use of mass in service, as it has official status and is listed in the V5c.

     Ray 

  • dawlishpete
    dawlishpete Forum Participant Posts: 16
    edited January 2021 #11

    Yes Ray! Thats the point I have been making. The caravan club will now totally ignore what you are suggesting and remain with one foot firmly planted in the 20th century ;-)

  • Tinwheeler
    Tinwheeler Forum Participant Posts: 23,142 ✭✭✭
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    edited January 2021 #12

    Have you contacted the club yet as was suggested?

  • dawlishpete
    dawlishpete Forum Participant Posts: 16
    edited January 2021 #13

    No point really. As Lutz has high-lighted, there is no fixed definition of kerbweight in law, therefore the "85%" rule is an irrelevant guess broadly swept into folklore with a will to make matters safer. In law the only weights that matter are the plated weights of the vehicle and caravan.

  • Tinwheeler
    Tinwheeler Forum Participant Posts: 23,142 ✭✭✭
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    edited January 2021 #14

    That’s exactly what I posted to you at the very beginning in your first thread. It is no more than a guide with no standing in law but you seemed to want the club to change to something else🤷🏻‍♂️

    https://www.caravanclub.co.uk/club-together/discussions/information-technical-tips-advice/caravans/outfit-matching-service/

     

  • dawlishpete
    dawlishpete Forum Participant Posts: 16
    edited January 2021 #15

    It must of been posted somewhere else or its been Deleted User.

     

  • Tinwheeler
    Tinwheeler Forum Participant Posts: 23,142 ✭✭✭
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    edited January 2021 #16

    Nope, follow the link, it's there.

  • Lutz
    Lutz Forum Participant Posts: 1,564 ✭✭✭✭
    edited January 2021 #17

    But there is a fixed definition of kerbweight in law, the trouble is that few stick to it. Instead, they create their own definition and expect others to know what it includes. The situation isn't made any easier by the fact that the vehicle manufacturer is not required to document kerbweight anywhere.

    Mass in running order (or mass in service as the V5c calls it) is no better because it only refers to the actual weight of the one vehicle that was submitted for type approval. Other vehicles of the same type or model but with further factory fitted options may weigh more, but their mass in running order remains the same.

    The closest documented figure is the 'actual mass' shown as item 13.2 in the vehicle's certificate of conformity. It is only a calculated value, but at least it does take into account the full equipment specification relating to that particular vehicle.

  • lornalou1
    lornalou1 Forum Participant Posts: 2,169
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    edited January 2021 #18

    surely the correct weight would be done on a weighbridge with full tank of fuel and no driver. you can then work out the match from that. peace of mind for yourself. 

  • armourer
    armourer Forum Participant Posts: 218
    edited February 2021 #19

    the answer to a vehicle kerb weight is on the log book

    simples

  • lornalou1
    lornalou1 Forum Participant Posts: 2,169
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    edited February 2021 #20

    Not all log books have the kerbweight on them and not all have the "mass in service" weight either. 

  • Extugger
    Extugger Forum Participant Posts: 1,293
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    edited February 2021 #21

    Possibly there's no legal requirement to publish the kerbweight of vehicles here in the UK was because all have manufacturing tolerances of +/- 5%, which in the pre-automation days, was probably the reason why 20 identical vehicles coming off the production line, would all weigh differently. With today's technology, they should all weigh the same (or have the same mass) but as I recall, the tolerances still remain. 

  • Lutz
    Lutz Forum Participant Posts: 1,564 ✭✭✭✭
    edited February 2021 #22

    I have yet to come across any log book which states the kerbweight.

  • Lutz
    Lutz Forum Participant Posts: 1,564 ✭✭✭✭
    edited February 2021 #23

    It is rare for 20 vehicles to come off the line with identical kerbweights. The manufacturing tolerances are still there even today and it is not very often that two vehicles in sequence have identical specification. Besides, kerbweight is an actual weight, not necessarily the weight of the vehicle as it left the factory. If the dealer (or the owner himself) has fitted any additional equipment, this would increase the kerbweight. Realistically, the kerbweight can only be established by a weighbridge check.

  • Rayrowe35
    Rayrowe35 Forum Participant Posts: 112
    edited February 2021 #24

    There is one situation where this matters. At least one insurance company stipulates that the caravan mtplm must not exceed the kerb weight of the car. Imagine the court case - the lawyers would be in clover!
    Ray

  • Lutz
    Lutz Forum Participant Posts: 1,564 ✭✭✭✭
    edited February 2021 #25

    It would be interesting to know where, in the case of a dispute, the insurance get their information from, because kerbweight is not documented anywhere.

  • ScreenName642F962777
    ScreenName642F962777 Forum Participant Posts: 14
    edited February 2021 #26

    So does this mean that e.g. with my Qashqai which has the following V5 weights: mass in service 1548 (meaning, I believe, the car plus all fluids including a full tank of petrol), max permissable mass 1960 (including everything, passengers, luggage, fluids, vehicle) and TPMTMT of 1800, then if I match this to a caravan of MIRO 1520 and max of 1700 fully laden then I am legally fine, as long as the max fully laden mass of trailer is 1700 which is below the TPMTMT of 1800.  Now, as an assessment of safety of towing the industry has this 85% concept for beginners, but this is not a legal requirement just an industry recommendation. Also, how can this 85% figure be the same for single and twin axles?  And for trailers with advanced stability control?  It seems a bit outdated, or should I say, not updated?

    Anyway, using thisIf I am pulling the caravan unladen i.e. 1520kg plus motor movers say 1545, then the mass of the car at 85% should be 1817.  The car has a mass in service of 1548, but take out weight of fuel then this is say 1500. So to get the car (excluding fuel) to 85% "safe for beginners" of the unladen caravan of 1520kg I need a weight of 1817, which is the car of 1500, me of 100, 225L of water in two large tanks on back seat, gives me 1,825kg, then on top of that the fuel tank fluctuates, but I will never go below 1,825kg.  The gross train mass will go as high as 1875+1520=3395 which is within V5 limit of 1960+1800=3,760 and within the 3500 limit before needing a B+E license.  And as an additional margin of error I have a twin axle and ALKO ATC system installed.  Anyone see a problem with this arrangement?

    For exaple if you give the twin axle some value (if not fof more stable towing then what is the value of twin axle?, ditto the ALKO ATC system) say 5%, then at 90% the car would only have to weigh 1716kg, namely the car itself at 1500, me at 100, then 125 litres of water , then the fuel can fluctuate on top.

  • Tinwheeler
    Tinwheeler Forum Participant Posts: 23,142 ✭✭✭
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    edited February 2021 #27

    Sorry, no way can I follow that.

    Legally you must not exceed the GTW as shown on your vehicle's plate, nor must you exceed the manufacturer's rated max towing limit for the car, or its max loading, or the MTPLM of the caravan. Also you must ensure you have the correct driving licence to entitle you to drive your outfit.

    Other than that, guidance is just that - sensible guidance for safety.

  • ScreenName642F962777
    ScreenName642F962777 Forum Participant Posts: 14
    edited February 2021 #28

    OK well how about this, why does this 85% guidance not vary for single and twin axle trailers?

  • Metheven
    Metheven Club Member Posts: 3,987 ✭✭✭
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    edited February 2021 #29

    I think the answer is 32.

  • Tinwheeler
    Tinwheeler Forum Participant Posts: 23,142 ✭✭✭
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    edited February 2021 #30

    Weight is weight irrespective of the number of axles. 

    In fact, the more axles you have, the heavier the trailer will be so the more difficult it becomes to find a heavy enough tow car.

  • ScreenName642F962777
    ScreenName642F962777 Forum Participant Posts: 14
    edited February 2021 #31

    No, weight is not weight when it comes to stability, that's why it makes a difference how you load the caravan and all the advice is to put heavy items over the axle, etc.  If the weight was strapped onto the roof you would become far less stable than if the weight was above the axle.