Axle ratings query

Rod Mac · Veteran Member

Axle ratings query

dabbler · Guru

The weight difference hasn't gone anywhere. The axle group rating (an engineered maximum) is a potential value not an actual value. That potential value should always be less than the legal compliance rated ATM or something dodgy has occurred. You need to be concerned with your actual values and the legal compliance values and if any one of your values exceed it's legal limit, the whole rig is illegal.

yobarr · Guru

Rod Mac wrote:
With all the discussions going on around weights I ask if there is anybody with knowledge on how the Cvan manufacturers determine the Ratings on the compliance plates.
My van has an axle group rating of 2800kg.(dual axle roller rocker leaf springs)
The compliance plate is stamped as follows.
The tare mass is 1409kg with 147kg tow ball (empty).
The GTM is 1662 and the ATM 1809 thus GTM + T/B is the ATM as rated by the manufacturer, so I ask with a payload of of 400kg on top of the tare of 1409kg bringing it up to the ATM of 1809kg so where did 991 kg disappear i.e. axle rating 2800kg minus ATM 1809 kg= 991kg.
I know that weighbridge figures show me with 200kg on the T/ball and GTM at 1950kg with ATM at 2150kg so yes I am over the Compliance plate figures but still a fair few kg's (650kg) from the Axle group maximum rating.
So where has the max allowed weight or difference on the Axle group to the ATM gone or is there a maximum percentage on the axle group, anybody have correct knowledge.
Rod Mac

Hi Rod....Monty will no doubt be able to tell you the exact rules,but I once had a van with axle group rating of 2800kg. However,GTM was only 1960kg and ATM was 2180kg,so it was useless,as tare was 1750kg.However,it was exceedingly easy to get that GTM up to 2800kg (the same as the axle group rating) and ATM to 3080kg.The limiting factor was that you are not allowed more than 1400kg on an axle that has 10 brakes and 16 wheels.I later put 12 brakes on it and got the GTM up to 3000kg and ATM to 3300kg.....Obviously an engineers inspection,and report,is required to get the new compliance plate,but it can be done with minimal fuss.Hope this helps you.Cheers

Iva Biggen · Senior Member

Apart from the axle group rating there are other considerations that have an effect on trailer weights. For one, chassis design is of great importance as is wheel and tyre size, brakes and suspension.

Personally I would place very little credence on the information provided by happy hour caravan park or forum engineers, but source an engineer that has actual qualifications with assessments for structural and transport equipment based specifications with regard to the actual maximum allowances of all the assessable specifications and have that engineer provide you with the necessary forms and reports to have your van upgraded to be compliant with your equipment capabilities.
Anything less and you will always be in a quandary as to what your equipment may be allowed to carry.
A qualified engineer will be able to provide you the documentation to have your specifications re assessed and a new compliance plate fitted as well as an update of information so your state registration details may be updated accurately to reflect your loading ability at the same time.
To answer your question, caravan manufacturers rate a caravan on the ability for their dealer to sell the heaviest van to the client with the lightest tow vehicle. If a weight on the compliance plate fits the story then it is really up to the owner if they have doubts to do the checks and balances. This may not be absolute with some dealers but is unfortunately an underlying factor in the industry.

What I would do is go to a weighbridge with an empty van and weigh it and check it against what it is indicated on the compliance plate.
Note the true tare weight.
Then either load it and weigh it again or at least do the estimation on what your ATM will be on your van. You may have to actually load it to assess ball weight and axle weight or GTM. Tow ball weight allowance will depend on your actual tow vehicle spec or your tow bar specifications.

An honest dealer should help you with all of this if you are buying new but second hand purchases can be a problem if these weight checks arent carried out prior to purchase.

Actually there are very few caravan dealers that can provide engineering assessments and even if they are qualified they generally arent prepared to put their approval on a van that they have had little or no input into the build and design.
Dealers are just that...dealers who sell caravans.

You also may want to consider that your van may be upgraded to carry a lot more weight that is on the original compliance plate but then that may snowball to a situation when now your loaded van may be too heavy to comply with your tow vehicle specifications.
There is no real definitive answer to your problem but you may start with finding a transport engineer that can provide you with the answers that will help you assess the final solution to your problem.

Good luck with your engineering assessment.

-- Edited by Iva Biggen on Wednesday 31st of July 2019 08:10:09 PM

-- Edited by Iva Biggen on Wednesday 31st of July 2019 08:29:54 PM

Baz421 · Guru

Rod Mac wrote:
With all the discussions going on around weights I ask if there is anybody with knowledge on how the Cvan manufacturers determine the Ratings on the compliance plates.
My van has an axle group rating of 2800kg.(dual axle roller rocker leaf springs)
The compliance plate is stamped as follows.
The tare mass is 1409kg with 147kg tow ball (empty).
The GTM is 1662 and the ATM 1809 thus GTM + T/B is the ATM as rated by the manufacturer, so I ask with a payload of of 400kg on top of the tare of 1409kg bringing it up to the ATM of 1809kg so where did 991 kg disappear i.e. axle rating 2800kg minus ATM 1809 kg= 991kg.
I know that weighbridge figures show me with 200kg on the T/ball and GTM at 1950kg with ATM at 2150kg so yes I am over the Compliance plate figures but still a fair few kg's (650kg) from the Axle group maximum rating.
So where has the max allowed weight or difference on the Axle group to the ATM gone or is there a maximum percentage on the axle group, anybody have correct knowledge.
Rod Mac

The simple answer is the ATM is limited by lowest of several factors as Iva Biggen has outlined ie chassis strength, monocoque strength (body plays a part), load distributon etc etc so the manufacturer "calculates" (I use that term VERY loosely) the ATM. The ATM will always normally (again I use that term loosely) be well less than axle rating(s).

Maybe read my post about GVM/GCM upgardes for the DMax - the thread was closed today.

Nevd · Senior Member

Rod, have you approached the manufacturer of your van to see if they are able to upgrade without any other certification?

In some vans there is some built-in leeway. Not that long ago, it was assumed by many that 400 kg for a dual axle and 300 kg for a single axle was the accepted market norm - even though the van may be capable of more.

Personally, I had a plate on the van that said the chassis (which included the suspension, wheels,) etc was rated 100kg more than the van's ATM. The tare weight on the compliance plate was noticeably higher than what the van weighed empty - the previous owner may have added a bit more than he said after the initial purchase. The manufacturer was happy to upgrade the ATM free and issue new compliance plate & covering letter for Qld Transport, as he knew the van was capable.

There have been other instances noted by forum members who have had similar success. Conversely, there have been many others who have had to go the more complex & costly engineer certified route.

When looking at a new Winnebago van a couple of years ago, the one we liked could be had with a payload of 400 kg, 500 kg, or 600 kg. I asked if the chassis or suspension was different, and was told no, it was just what the customer wanted so their maximum towing capacity wouldn't be exceeded - mainly aimed at Toyota Prado owners. I asked - "Why not get the maximum ATM for higher resale value later, and just load it according to their vehicle's capacity?". Apparently, ATM's and legalities aren't understood by everyone.

Rod Mac · Veteran Member

Hi and thanks to all for your input.

It seems to me to be that cvan manufacturers get an idea or design what the chassis can handle then put a strong enough axle, springs, wheels, tyres, and brakes under it, and fair enough.

The problem as I see it for thousands of cvan owners is the amount we/they are limited to carry, seriously a 400kg payload can disappear pretty quickly.

Add an extra water tank, extra spare wheel, Portable BBQ, spare gas cyl, awning, annex, bedding, clothing, food, generator, toolboxes, kitchen appliances etc...and quite easily you are over legal ATM. (n.b. this is not a list of things that I carry, but plenty do)

And as ridiculous as this following sentence/query may seem, does the ATM also then include/allow for 2 people of 100kg each (and sometimes children) actually sitting/sleeping in the van stationary ? if it does not allow for that, then the van is over the ATM even though it is not being towed, food for thought or maybe not.

The cvan industry/manufacturers really need to be called out to see what owners take with them and start making cvans with big enough ratings to be realistic.

Once again thank you all for your input.
Rod Mac

yobarr · Guru

Rod Mac wrote:
Hi and thanks to all for your input.

It seems to me to be that cvan manufacturers get an idea or design what the chassis can handle then put a strong enough axle, springs, wheels, tyres, and brakes under it, and fair enough.
The problem as I see it for thousands of cvan owners is the amount we/they are limited to carry, seriously a 400kg payload can disappear pretty quickly.
Add an extra water tank, extra spare wheel, Portable BBQ, spare gas cyl, awning, annex, bedding, clothing, food, generator, toolboxes, kitchen appliances etc...and quite easily you are over legal ATM. (n.b. this is not a list of things that I carry, but plenty do)
And as ridiculous as this following sentence/query may seem, does the ATM also then include/allow for 2 people of 100kg each (and sometimes children) actually sitting/sleeping in the van stationary ? if it does not allow for that, then the van is over the ATM even though it is not being towed, food for thought or maybe not.
The cvan industry/manufacturers really need to be called out to see what owners take with them and start making cvans with big enough ratings to be realistic.
Once again thank you all for your input.
Rod Mac

Hi Rod....interesting question regarding occupant being included in the ATM? When the van is stationary,perhaps ATM becomes GVM because the the van us not being towed? (The T in ATM). I do,of course,jest.Cheers

-- Edited by yobarr on Thursday 1st of August 2019 05:08:03 PM

blaze · Guru

Rod Mac wrote:
Hi and thanks to all for your input.

It seems to me to be that cvan manufacturers get an idea or design what the chassis can handle then put a strong enough axle, springs, wheels, tyres, and brakes under it, and fair enough.

The problem as I see it for thousands of cvan owners is the amount we/they are limited to carry, seriously a 400kg payload can disappear pretty quickly.

Add an extra water tank, extra spare wheel, Portable BBQ, spare gas cyl, awning, annex, bedding, clothing, food, generator, toolboxes, kitchen appliances etc...and quite easily you are over legal ATM. (n.b. this is not a list of things that I carry, but plenty do)

And as ridiculous as this following sentence/query may seem, does the ATM also then include/allow for 2 people of 100kg each (and sometimes children) actually sitting/sleeping in the van stationary ? if it does not allow for that, then the van is over the ATM even though it is not being towed, food for thought or maybe not.

The cvan industry/manufacturers really need to be called out to see what owners take with them and start making cvans with big enough ratings to be realistic.

Once again thank you all for your input.
Rod Mac

does not matter what the loading is on a parked up van, you could stack a ton of wood on your drawbar if you like. No allowance for people as they are not allowed in a moving van. I do agree that the industry has a lot to answer to in regard to weight and delivery standards

cheers

blaze

Baz421 · Guru

Rod Mac wrote:
Hi and thanks to all for your input.

It seems to me to be that cvan manufacturers get an idea or design what the chassis can handle then put a strong enough axle, springs, wheels, tyres, and brakes under it, and fair enough.

The problem as I see it for thousands of cvan owners is the amount we/they are limited to carry, seriously a 400kg payload can disappear pretty quickly.

yes that is the issue for many of us

And as ridiculous as this following sentence/query may seem, does the ATM also then include/allow for 2 people of 100kg each (and sometimes children) actually sitting/sleeping in the van stationary ? if it does not allow for that, then the van is over the ATM even though it is not being towed, food for thought or maybe not.

ATM applies on road use, off road or parked not an issue

Once again thank you all for your input.
Rod Mac

Rod Mac · Veteran Member

Hi Baz, yep just me being mischievous,(sick sense of humour !) but heaven help if something does happen and you get a Lawyer involved with arguments of straining and damaging components, as far fetched as that may be, but in this day and age of litigation who knows what absurd arguments can be put up.

It will be interesting to hear the outcome of the Court Case in the 'Walcha' accident and subsequent charges placed on the driver and then what repercussions that may have.

Rod Mac

Baz421 · Guru

Rod Mac wrote:
Hi Baz, yep just me being mischievous,(sick sense of humour !) but heaven help if something does happen and you get a Lawyer involved with arguments of straining and damaging components, as far fetched as that may be, but in this day and age of litigation who knows what absurd arguments can be put up.
It will be interesting to hear the outcome of the Court Case in the 'Walcha' accident and subsequent charges placed on the driver and then what repercussions that may have.
Rod Mac

OK fair enough Cheers

dabbler · Guru

Charges on the Walcha fatal accident don't only relate to an overweight van but a van that was too heavy to be legally towed by the vehicle in use (Prado). A number of negligent driving charges as well as procedural charges also stand. Early press reports suggested the towbar fitted wasn't even rated at the max of the Prado's tow capacity and that the driver was also charged with this offence. That detail isn't clear in current reports but may just be the reporting. The case is being heard in court now.

dabbler · Guru

The last post should read "the towbar wasn't at the Prado's max capacity and the van exceeded both fitted towbar and vehicle max capacity".

montie · Guru

Rod Mac wrote:
With all the discussions going on around weights I ask if there is anybody with knowledge on how the Cvan manufacturers determine the Ratings on the compliance plates.
My van has an axle group rating of 2800kg.(dual axle roller rocker leaf springs)
The compliance plate is stamped as follows.
The tare mass is 1409kg with 147kg tow ball (empty).
The GTM is 1662 and the ATM 1809 thus GTM + T/B is the ATM as rated by the manufacturer, so I ask with a payload of of 400kg on top of the tare of 1409kg bringing it up to the ATM of 1809kg so where did 991 kg disappear i.e. axle rating 2800kg minus ATM 1809 kg= 991kg.
I know that weighbridge figures show me with 200kg on the T/ball and GTM at 1950kg with ATM at 2150kg so yes I am over the Compliance plate figures but still a fair few kg's (650kg) from the Axle group maximum rating.
So where has the max allowed weight or difference on the Axle group to the ATM gone or is there a maximum percentage on the axle group, anybody have correct knowledge.
Rod Mac

Rod,

This is a contentious question.

Van Manufacturers set their ATM mainly based on market demand to bring the van within certain tow vehicle capacities. They usually give you around 300kg payload for a single axle van and 400kg for a tandem axle, usually with the option of a free ATM upgrade before the van is registered. Many buyers make their decision based on the towing capacity of their current vehicle. For instance a buyer with a vehicle that has say 2500kg towing capacity will not even consider a van with an ATM of 2800 kg.

Obviously the rated ATM must not exceed the lowest rated component of the chassis, axles,suspension or tyres.

The Axle Group Rating is not set by the van manufacturer but by the chassis manufacturer and in most circumstances you can get an upgrade close or equal to the AGR. The van manufacturer will normally do this free of charge before the van is registered but an engineer's certification is necessary if the van is already registered.

Most dealers discuss this with prospective buyers at sale time and agree on an appropriate ATM and Payload when the van is ordered.

There are those who believe that the ATM should always be set to the maximum limit which is Axle Group Rating and you only load the van to your towing capacity which is perfectly legal. Personally I do not agree with this course of action.

-- Edited by montie on Friday 9th of August 2019 04:36:21 PM

Peter_n_Margaret · Guru

montie wrote:
There are those who believe that the ATM should always be set to the maximum limit which is Axle Group Rating and you only load the van to your towing capacity which is perfectly legal. Personally I do not agree with this course of action.

Why do you not agree?

Cheers,

Peter

montie · Guru

Peter_n_Margaret wrote:
montie wrote:
There are those who believe that the ATM should always be set to the maximum limit which is Axle Group Rating and you only load the van to your towing capacity which is perfectly legal. Personally I do not agree with this course of action.
Why do you not agree?
Cheers,
Peter

Pete,

I was expecting your arrival blankstare .

I remember a few years back on another forum this subject was debated hotly and still remains contentious.

Any combination where the van ATM exceeds the tug towing capacity raises some concerns for me.

Firstly in the event of a serious or even fatal accident where forensic investigators are involved and a subsequent court action where, as in a recent event, people are charged, what argument will the prosecutor put forward.

"Your honour the caravan involved in this accident was capable of being legally loaded way beyond the towing capacity of the defendent's vehicle."

Why take that risk...my view...the towing capacity of your tug should ideally exceed but at best equal the van ATM.

In addition where a random roadside check happens and your van ATM exceeds your towing capacity.....red light for the nice officer to look further straight away.

Finally, there is no advantage in owning a van with a higher ATM than the towing capacity because you can only load to the tow capacity anyway!

Peter_n_Margaret · Guru

Firstly in the event of a serious or even fatal accident where forensic investigators are involved and a subsequent court action where, as in a recent event, people are charged, what argument will the prosecutor put forward.
"Your honour the caravan involved in this accident was capable of being legally loaded way beyond the towing capacity of the defendent's vehicle."

Totally irrelevant. The question is whether the tug tow capacity was exceeded, or not.

In addition where a random roadside check happens and your van ATM exceeds your towing capacity.....red light for the nice officer to look further straight away.
No more a red light than having a speedo that goes to 200kph, or some other number that exceeds the speed limit. Same applies to trucks and assumptions are not made unless they are weighed.

Finally, there is no advantage in owning a van with a higher ATM than the towing capacity because you can only load to the tow capacity anyway!

There are indeed advantages to be able to use capacity that would not otherwise be unavailable if the tug has capacity in excess of the ATM which is very often, and there are advantages when changing to a tug with higher capacity and advantages in resale value. The costs involved by caravan owners who wish to increase their ATMs are significant and ongoing and in many cases it is simply a case of silly limits imposed in the first instance.

The ridiculous random imposition of 300kg or 400kg simply can not be justified.

Any load limit whether on the van or on the tug can be exceeded. The owner MUST know what those limits are and what their weights are and comply. Having an artificially low limit will not change that.

Cheers,

Peter

-- Edited by Peter_n_Margaret on Friday 9th of August 2019 07:49:52 PM

montie · Guru

Peter_n_Margaret wrote:

Firstly in the event of a serious or even fatal accident where forensic investigators are involved and a subsequent court action where, as in a recent event, people are charged, what argument will the prosecutor put forward.
"Your honour the caravan involved in this accident was capable of being legally loaded way beyond the towing capacity of the defendent's vehicle."

Totally irrelevant. The question is whether the tug tow capacity was exceeded, or not.

In addition where a random roadside check happens and your van ATM exceeds your towing capacity.....red light for the nice officer to look further straight away.
No more a red light than having a speedo that goes to 200kph, or some other number that exceeds the speed limit. Same applies to trucks and assumptions are not made unless they are weighed.

Finally, there is no advantage in owning a van with a higher ATM than the towing capacity because you can only load to the tow capacity anyway!

There are indeed advantages to be able to use capacity that would not otherwise be unavailable if the tug has capacity in excess of the ATM which is very often, and there are advantages when changing to a tug with higher capacity and advantages in resale value. The costs involved by caravan owners who wish to increase their ATMs are significant and ongoing and in many cases it is simply a case of silly limits imposed in the first instance.
The ridiculous random imposition of 300kg or 400kg simply can not be justified.
Any load limit whether on the van or on the tug can be exceeded. The owner MUST know what those limits are and what their weights are and comply. Having an artificially low limit will not change that.
Cheers,
Peter

-- Edited by Peter_n_Margaret on Friday 9th of August 2019 07:49:52 PM

Like I said Pete I was expecting your arrival.

There is no point in us beating this drum all over again...you have your opinion and I have mine.

That's what forums are all about. blankstare

Peter_n_Margaret · Guru

It is not about opinions Monty, it is about what the law requires, that is clear and you are way out of step with that.
Cheers,
Peter

montie · Guru

Peter_n_Margaret wrote:
It is not about opinions Monty, it is about what the law requires, that is clear and you are way out of step with that.
Cheers,
Peter

Pete

Legally a van manufacturer may set his ATM at his discretion.

There is no legal requirement for him to set it at AGR.

Pete, whether you like it or not that is the current legal situation...nothing to do with my "stepping" situation. blankstare

So you are right...it's not about opinions....it's about what is legal.

Peter_n_Margaret · Guru

Nor is there any legal requirement to restrict it to 300kg or 400kg above tare which is common and makes no sense whatever for the customer - but clearly they don't care what is the best for the customer?
Cheers,
Peter

montie · Guru

Peter_n_Margaret wrote:
Nor is there any legal requirement to restrict it to 300kg or 400kg above tare which is common and makes no sense whatever for the customer - but clearly they don't care what is the best for the customer?
Cheers,
Peter

In your opinion Pete, which you are entitled to.

But the legal situation does not change. That's the reality.

BTW Pete I am entitled to my opinion also....still doesn't change the legal situation.

To summarise....the van manufacturer can set his ATM rating at his discretion within legal limitations....no legal requirement to match Axle Group Rating.

It is not illegal to tow a van with an ATM that exceeds the towing capacity provided it is only loaded to the towing capacity. I would not recommend it for the reasons already explained.

Now I'm getting dizzy going around in circles and I have a big day on the golf course tomorrow so goodnight all....sleep well blankstare

yobarr · Guru

As a regular reader of posts on this forum,I quickly learned that both Monty and Peter know what they are talking about. This is why I am surprised that there now is disagreement on something that,to me,is so blatantly obvious.Sorry Peter,but Monty is correct.Cheers

Peter_n_Margaret · Guru

Monty is correct in that the manufacturer's can and do artificially reduce the legal load capacity below the axle group capability.
My contention is that it is not legally required, serves no useful purpose and that it does nothing to improve safety, but it does often inconvenience the owner and often costs the owner money to rectify. We see a constant stream of caravan owners on forums asking how to rectify this. None ever wish (or need) to reduce their ATM.
It is interesting that this occurs with caravans, but not with garden trailers, horse trailers, or other trailers. Why is this?
Cheers,
Peter

yobarr · Guru

Peter_n_Margaret wrote:
Monty is correct in that the manufacturer's can and do artificially reduce the legal load capacity below the axle group capability.
My contention is that it is not legally required, serves no useful purpose and that it does nothing to improve safety, but it does often inconvenience the owner and often costs the owner money to rectify. We see a constant stream of caravan owners on forums asking how to rectify this. None ever wish (or need) to reduce their ATM.
It is interesting that this occurs with caravans, but not with garden trailers, horse trailers, or other trailers. Why is this?
Cheers,
Peter

Hi Peter....Is it possible that manufacturers reduce their legal load capacity below the axle group capacity to cater to the huge number of people who apparently have absolutely NO understanding of weights? How many people know that they can legally use a car with a 3000kg towing capacity to tow a van with an ATM of 3500kg provided that the loaded van weighs no more than 3000kg? If some of the posts on this site are any indication,I would suggest that the answer is very few.If people do not understand weights,they may well walk away from a van purchase simply because the ATM is greater than the tow capacity of their car? Those in the know would be well aware that increasing the ATM is not difficult if the axle group has a higher rating.Cheers.

-- Edited by yobarr on Saturday 10th of August 2019 05:59:26 PM

Peter_n_Margaret · Guru

If someone has "absolutely NO understanding of weights" they will not be affected either way, unless manipulated by the dealer or manufacturer.
It was generally believed that it was not legal to tow a van of any weight if the ATM exceeded the tow capacity of the tug. Some manufacturers and dealers clearly still believe this and Monty also believed that until relatively recently, but now accepts that this is NOT the case in law. I believe that this is a hang over from those mistaken understandings of the law.
Dealers and manufacturers should be actively dissuaded from this unsound and unnecessary practice.

The difficulty in increasing the ATM to a higher rating varies. If the manufacturer still exists and is cooperative it can be very easy as you say. If the manufacturer is gone or uncooperative it is harder and is likely to cost the owner money, at the very least. But it is something that need never arise.
There are disadvantages to owners in the current practice. I know of no advantages.
Cheers,
Peter

-- Edited by Peter_n_Margaret on Saturday 10th of August 2019 06:48:08 PM

montie · Guru

Firstly, let's be clear I am not a caravan manufacturer I am a semi retired dealer.

Van manufacturers, the same as car and truck manufacturers, set their ATM ratings to meet market demand.
I can quote Iveco here as an example that comes immediately to mind where they set their plated GVM at 4490kg to meet car licence requirements when they offer a GVM upgrade to those with LR licences.

Van manufacturers offer their products to the most available market by setting tow friendly ATMs with upgrade options freely available to those who require them. Everything is declared and above board so there is no "manipulation". This practice is perfectly legal and van manufacturers have every right to make their products available to the broadest possible market.

I do not recommend the practice of ATM exceeding tug towing capacity for reasons already posted earlier.
Another problem arises for selling dealers offering a van with an ATM rating greater than the vehicle tow capacity...it's called the Consumer Act.
Buyers have a reasonable expectation that the new van they purchase can legally be loaded to it's max ATM and if this exceeds the towing capacity of their vehicle they have a possible not fit for purpose claim. We rarely encounter a situation where ATM exceeds tow capacity but if it does happen we insist on a signed disclaimer from the buyer.

Despite the fact that a rare minority believe that ATM should equal Axle Group Rating there is no manufacturer that I know of who does it.

Peter_n_Margaret · Guru

montie wrote:
Van manufacturers, the same as car and truck manufacturers, set their ATM ratings to meet market demand.
I can quote Iveco here as an example that comes immediately to mind where they set their plated GVM at 4490kg to meet car licence requirements when they offer a GVM upgrade to those with LR licences.

That is totally irrelevant Monty. It would be relevant to reduce a possible van ATM from (say) 4.8T to 4.495T to keep it in the "light" category, but it does nothing to the licence requirements or anything else to reduce a possible ATM of (say) 3.4T to (say) 2.8T.

Despite the fact that a rare minority believe that ATM should equal Axle Group Rating there is no manufacturer that I know of who does it.

I think pretty much every manufacturer of light trailers (other than caravans) does it. The law regarding all light trailers in regard to ATM mass and towing is the same.

Cheers,

Peter