Missing MTPLM

[chrisbee1]

As I’ve just fitted a mover to my ‘van I thought it would be prudent to up-rate the MTPLM to the maximum specified by Bailey at a cost of over £60.00 in total. Along with the weight sticker for the van showing 1420Kgs was a new certificate from the NCC showing the under gear actually has a MTPLM of 1500KGs. Where’s the other 80Kgs gone?

 

[Gafferbill]

...... the chassis manufacturer decides the maximum weight his vehicle can carry and this must not be exceeded in law.
.......the caravan manufacturer decides the maximum weight his vehicle can carry
..... this then becomes 'The Whole Vehicle' MTPLM. and must not be exceeded by law.

Some heavy goods vehicles for example have a design MTPLM of 38 tons but are down plated to a legal maximum MTPLM of 24 tons.
In this case it is usually for taxation reasons.
In the case of caravans the difference is usually to do with the construction materials used and how any payload is likely to be distributed.

 

[otherclive]

Tyre loadings will also reflect the makers MTPLM. Some motorhome drivers down plate their vehicles to 3500kg or below to avoid the more onerous medical regime when they reach 70yrs.

 

[RogerL]

The C1 licence requirement (to drive over 3,500kg MAW) at age 70 is just a self-declared medical questionairre.
The more extensive requirement and expensive medical examination is only needed to drive commercial vehicles and/or mini-buses - this isn't needed for non-commerciail vehicles like motorhomes.

 

[JTQ]

Along with the weight sticker for the van showing 1420Kgs was a new certificate from the NCC showing the under gear actually has a MTPLM of 1500KGs. Where’s the other 80Kgs gone?

Part of the van's mass is on the hitch so it could simply mean 1420kgs on the axle 80 on the hitch equating to the van's quoted 1500kg total mass?

 

[chrisbee1]

In the case of caravans the difference is usually to do with the construction materials used and how any payload is likely to be distributed.

I totally understand what you're saying Gafferbill and of course will abide by the plated weight as specified by Bailey. I just find it a bit strange that they "lose" me 80Kgs when the mover I have fitted is hanging on the "under body" so won't have any effect on the interior payload. The extra allowance I was after is for a weight fitted right by the axle and low down so don't really see what possible impact it could have on Bailey's part of the build.

 

[Gafferbill]

Chrisbee........I agree with your science but I would suspect Bailey just have a set procedure they follow when someone asks for a MTPLM upgrade.

If you think about it they are on to a winner in every respect........ Your caravan model will attract more buyers if they keep that model's MTPLM lower........ making it available to a larger range of tow vehicles.
Then if someone wants an upgrade they charge £60 for a new plate and a certificate.

My own caravan sits on a 1300kgs chassis.... the tyres can handle 1440kgs.... but Swift's MTPLM for it is 1150kgs!!!!

 

[otherclive]

In comparison my Bordeaux had a load upgrade from 1340kg to 1400 kg but the OEM tyres were only rated to 1420kg total and the new tally plate kept the tyres to their original pressure. Subsequent discussion with Bailey led them to recommend a tyre upgrade too and the tyres load index is now 102/104 which gives a far larger margin over MTPLM.

 

[Lutz]

In comparison my Bordeaux had a load upgrade from 1340kg to 1400 kg but the OEM tyres were only rated to 1420kg total and the new tally plate kept the tyres to their original pressure. Subsequent discussion with Bailey led them to recommend a tyre upgrade too and the tyres load index is now 102/104 which gives a far larger margin over MTPLM.

Of course, there is nothing wrong with tyres with a combined load rating of 1800kg on a caravan with an MTPLM of only 1400kg, but such a large margin is really unnecessary. By design, tyres already have a 10% safety margin over their load index anyway. Besides, as the noseweight is included in the MTPLM, the actual axle load is less than the MTPLM. Also, the load rating is based on the tyre's load carrying capacity at the maximum speed allowable according to its speed index. Caravans are normally not towed at anything like this speed. A recommedation of a further 10% safety margin over that already provided is therefore more than adequate.

 

[otherclive]

You are right with your feedback, but the problem came from the fact that the chsoice of tyres at slightly higher total load ratings ( ie 1500kg) was not available and I was keen to fit a commercially based tyre from a recognised brand rather than the tyres as fitted originally. Since buying the van makers have tended towards tyres from recognised makers and the wheel sizes have hence given buyers a wider choice. The good news is that the wardrobes are all still in place!!

 

[colin-yorkshire1]

hi,
I had our MTPLM increased by bailey, at a cost of £50 after fitting the mover as the user payload had effectivley been reduced below 100kg, the increase was only 36kg which I thought was a bit mean when it too sits on a 1300kg chassis and brought the new MTPLM still well below 1100kg.
but as the advert says "every little helps"

 

[chrisbee1]

I had our MTPLM increased by bailey, at a cost of £50 after fitting the mover as the user payload had effectivley been reduced below 100kg, the increase was only 36kg

A real bargain. I only got 20Kgs for £60 plus

 

[RogerL]

The original intention of the term "Maximum Technical Permitted Laden Mass" (MTPLM) was to use the highest permissible rating based on the lowest of all the factors - chassis, suspension, brakes, tryes, bodyshell. It's a definition which means that you can't increase it without mechanically upgrading whichever is the lowest factor.
But in reality, UK manufacturers chose to use a minimum figure to make their caravans appeal to more buyers without increasing the size of their towcars - this makes a plate upgrade possible without any mechanical upgrading.
The current attitude varies among UK manufacturers - Lunar offer a FoC upgrade at time of order to the figure that's a genuine maximum for the running gear - Bailey charge for an increase which still isn't the maximum - I don't know what Coachman, Elddis and Swift do.
It beggars belief that Bailey's customers put up with this minimalist service - but they're a hardy lot !

 

[chrisbee1]

Indeed we are (through necessity)

 

[RogerL]

Indeed we are (through necessity)

Is it necessary ?
I have a leaking Bailey sat on my drive waiting to be replaced with a different brand - unlike many Bailey owners I got 12 years dry use out of mine before the leaks started !

 

[colin-yorkshire1]

Indeed we are (through necessity)

Is it necessary ?
I have a leaking Bailey sat on my drive waiting to be replaced with a different brand - unlike many Bailey owners I got 12 years dry use out of mine before the leaks started !

Is it necessary ? no it is not!! whether a van leaks or stays dry is down to materials and construction techniques and not weight that is a seperate issue.
neither is the question of why Bailey charge for a upgrade while other give one free,
the real question is, the size of the increase and the reason behind it, I agree with your analysis of why a MTPLM it set low but really the sums dont add up, surely it is down to critical mass rather than a mythilogical figure plucked out of thin air.
take two vans identical construction with the same equipment built on the same chassis but one is 1 meter longer say because one has long front bunks and the other short ones, now of course the longer one will be heavier because of the extra materials used but the weight of these can easily be calculated say 100kg, one would think that the difference between the vans MAM would be 100kg you would be wrong!, as the shorter one would be marketed at a different type of customer, and therefore the weight target set much lower so it could be towed by a smaller vehicle,
asking for a weight increase should involve a genuine attempt by the manufacturer to give the customer what they require but market stategy prevents this and you get a few kilo's here and there, when in fact 1or 2 hundred kilos should be possible,
take my van it's a 380/2 and identical to the 420/4 same chassis, same layout exept for the central dinette "and upper bunk"
the difference in MIRO is 75kg but the diference in MTPLM is 147kg, there is no reason I can see why a increase of 100kg should not have been possible, given that the MTPLM of the 420/4 could also be increased,
exept of course that it would push the vans weight above the 1100kg threshold and not fit in with the target market,

 

[RogerL]

Colin - I think the first part of my post answers your question.
Deliberately downrating the original MTPLM to market to a wider audience is understandable, even if disliked - but offering an upgrade that still isn't the maximum is perverse.

The original intention of the term "Maximum Technical Permitted Laden Mass" (MTPLM) was to use the highest permissible rating based on the lowest of all the factors - chassis, suspension, brakes, tryes, bodyshell. It's a definition which means that you can't increase it without mechanically upgrading whichever is the lowest factor.
But in reality, UK manufacturers chose to use a minimum figure to make their caravans appeal to more buyers without increasing the size of their towcars - this makes a plate upgrade possible without any mechanical upgrading.
The current attitude varies among UK manufacturers - Lunar offer a FoC upgrade at time of order to the figure that's a genuine maximum for the running gear - Bailey charge for an increase which still isn't the maximum - I don't know what Coachman, Elddis and Swift do.
It beggars belief that Bailey's customers put up with this minimalist service - but they're a hardy lot !

 

[JTQ]

It gets even more ludicrous where a caravanner gets pulled in by Vosa and is overwieght but within the ratings of the components. He being over the plated MTPLM is deemed "unsafe" whereas if he had posted off £60 or whatever he would have been "safe".
This all comes back to our unique British fixation with the 85% mass ratio recommendation and the manufacturers playing with it to have the biggest market.

 

[RogerL]

It's no different to a truck driver in a 44 tonner which has been down-plated to 28 tonnes being stopped and prosecuted for being over 28 tonnes.
It's not unique to UK manufacturers - a number of German models can have their MTPLM upgraded in several 100kg steps - but the necessary engineering upgrades are included in that option price.
It's not really to do with the 85% Towing Ratio recommendation either - under EC regulations, post-1997 licence holders with B-only licence holders were restricted to towing trailers at no more than 100% Towing Ratio - this ratio is calculated using the MTPLM on the rating plate so the method of determing MTPLM affects any ratio used - this restriction is being removed, in the next few months I believe.

 

[ProfJohnL]

Down rating MTPLM's is used by caravan manufactures to make their products accessible to a wider driving public - mainly those who only have the B licence entitlement. It should be noted that not all models can have their MTPLM increased.

Its not directly aimed at the 85% suggestion, but it certainly can help those with such an interest.

this restriction is being removed, in the next few months I believe.

Its not clear at the moment whether the change to the restriction will be retrospective or not. In the past such changes have only been applied to drivers taking tests on or after the applicable date.

Its quite possible there will be swathe of drivers for whom the 100% ratio limit still applies.

 

[Lutz]

It's not unique to UK manufacturers - a number of German models can have their MTPLM upgraded in several 100kg steps - but the necessary engineering upgrades are included in that option price.

That's correct. My caravan has an ex-works upgrade of 200kg.

 

[colin-yorkshire1]

Down rating MTPLM's is used by caravan manufactures to make their products accessible to a wider driving public - mainly those who only have the B licence entitlement. It should be noted that not all models can have their MTPLM increased.

Its not directly aimed at the 85% suggestion, but it certainly can help those with such an interest.

hi, sorry John, I disagree, and think that the crux of the matter IS the tow ratio, and the main reason some MTPLM's are downgraded.
small lightweight vans like mine are no doubt targeted at the new to caravanning and those wishing to tow thier vans with smaller cars. now given that the average small car will be in the 1100 to 1300kg range downgrading the MAM to as low as possible catches more of these in the net, the 85% recommendation reduces this even further and one reason I don't like it.
my van had a MTPLM of 1022kg standard and was only increased 36kg to 1058kg if you take 85% of the highest figure it still falls within the tow limit of such cars, where as a increase of 150kg it would not. yet there is no valid reason why such an increase would not be possible, it sits on the same chassis as the bigger model ie 1300kg so no upgrading is required on that, it has the same construction and in fact being smaller probably more ridgid than the bigger van the MIRO on the vans is only 75kg yet the MTPLM's are 200kg different, most of it in user payload (assuming a 4 berth would need more payload) and a bigger tow car,
so in my view the ratio of van to car is more than just a coinsidance and part of the problem.

 

[RogerL]

The 85% has only ever been a recommendation - if you want to buy a bigger, heavier caravan you can.
Manufacturers' methodology in determining MTPLM doesn't require you to stick to 85%.

 

[otherclive]

One of the principal reasons that I have not bought a new van is the increasing MTPLM with no commensurate increase in payload. Why UK makers can't give buyers the choice of an increased payload which may actually mean some engineering changes just shows how little they value the customer. My current van has as 250kg payload within an MTPLM of 1400kg which allows us to live comfortably when away for extended trips. Some of the current payloads for so called family vans are more akin to a backpackers holiday kit!! The recent redefinition of payload against a few component now deemed to be within the MRO fails to disguise the trend to lower payloads.

 

[RogerL]

The user payload calculation hasn't changed - it's still based on the same multiple of the caravans interior length in metres plus another multiple of the number of berths. The old method of quoting payloads as essential items plus user payload has simply changed by including essential items in the MIRO, giving an impression of heavier caravans with an impression of lower payloads - but in reality nothing changed.
It is true of course that caravans have been getting heavier, year on year, sincle the early '80s. back then a mid-range 5-berth was 650kg net and 800kg gross - I guess they're double that or more, in terms of net weight.