Thread: GVM Question Again

I understand the Gross Train Weight to be 3,240kg GVM and 3,500kg for the trailer. This assumes a tow ball weight of 150kg. Any tow ball weight over 150kg would reduce the GVM by as much, with 350kg on the tow ball you would reduce the GVM to 3,040kg.

From the manual:
If the vehicle is loaded to the maximum Gross Vehicle Weight (GVW), the nose weight of the multi-height drop plate tow ball is limited to 150 kg, so that the maximum rear axle weight is not exceeded. To increase the nose weight to the maximum 250 kg, the GVW should be reduced by 100 kg.

and
Australia only: The nose weight must be a minimum of 7% of the gross caravan/trailer weight, up to a maximum of 250 kg. When using the detachable trailer hitch receiver, see FITTING THE DETACHABLE TRAILER HITCH RECEIVER (Australia only), the nose weight can be increased to 350 kg if the GVW is reduced by 200 kg.

Ron

Originally Posted by IndusD4

I understand the Gross Train Weight to be 3,240kg GVM and 3,500kg for the trailer. This assumes a tow ball weight of 150kg. Any tow ball weight over 150kg would reduce the GVM by as much, with 350kg on the tow ball you would reduce the GVM to 3,040kg.

From the manual:
If the vehicle is loaded to the maximum Gross Vehicle Weight (GVW), the nose weight of the multi-height drop plate tow ball is limited to 150 kg, so that the maximum rear axle weight is not exceeded. To increase the nose weight to the maximum 250 kg, the GVW should be reduced by 100 kg.

and
Australia only: The nose weight must be a minimum of 7% of the gross caravan/trailer weight, up to a maximum of 250 kg. When using the detachable trailer hitch receiver, see FITTING THE DETACHABLE TRAILER HITCH RECEIVER (Australia only), the nose weight can be increased to 350 kg if the GVW is reduced by 200 kg.

Ron

Ron
Thanks for the reply.

I sort of read the manual as you do but that does not make sense - to me.

eg

The GVM of the car is fixed as per placard on the car and would be what any inspection would use.

If you don't tow anything then as per reading of the manual your GVM is 3240kg
If you tow something with TBM of 150kg then the GVM is still 3240kg
However if your were already at 3240kg then surely your car would then have a mass of 3240+150kg and would be over the limit when measured.

However if talking about GCM or as the manual calls it GTW I think the 150kg is incorporated into the GCM/GTW and does not effect the GVM of the car.

Mind you if you were pulled over for an inspection I am unsure how you would explain this to them as they would just go on the figures shown and your GVM would appear over in both interpretations.

Richard

Richard

However if your were already at 3240kg then surely your car would then have a mass of 3240+150kg and would be over the limit when measured.

The 150kg you are quoting is not extra weight/mass. It is just the amount that is pushing down on the tow ball from the weight of the trailer. Not an extra 150kg you tow along.

With 150kg of weight on the tow bar your Gross Train Weight is still 3240+3500 (6740kg). With 350kg of weight on the tow ball, this is a reduced 3040+3500 (6540kg).


Hope that helps

Ron

To me it is very confusing, especially when all apples are in the air and you thought you were juggling oranges.
This link may explain it better plus other caravan and towing info
Episode 01: Keeping it Legal – Weights and Insurance - Full Episodes - Practical Guide to Modern Towing

As I see it, the most confusion in this area comes from the talk of tow ball weights.

You cannot (legally) exceed any of; GVM, GCM (GTW), towball/bar capacity, or permitted axle weights as per the placard on the vehicle (unless there is a mod plate fitted.)

10% TBW is a furphy. It was put out as an easy to remember formula, but is not in any legal document I have ever seen. If you add 350kg to the towbar, it adds 350kg to the GVM. This is partially transferred to the front axle of the tow vehicle (particularly in the case of air suspension.)

The only way to be certain what you have in the way of weights is to load everything up as if you are going on a trip - including the amount of water you would normally carry in tanks, extra fuel cans, full fridges, etc. Then go to a weighbridge. Make sure the weighbridge has a flat access/exit apron.

Weigh the front axle of the tow vehicle, write this down. Drive the tow vehicle onto the weighbridge, so the caravan jockey wheel is just short of the weighing plate. Write the weight down. Unhook the 'van. Write the weight down. Hook the 'van back up, and drive completely onto the 'bridge. Write the weight down. As you drive off the bridge, you can unhook again, and weigh just the 'van. Write the weight down. Split weigh the 'van axles as you are leaving the weighbridge. Write the weights down.

Now, sit down with your beverage of choice, and by using the weights you have written down, you can work out what weights you have where, including the weight distribution of the van axles (more important in my view, than towball weight).

A Transport Department or Police Officer (or insurance adjuster) is not going to be interested in percentages, or weight transfer to/from axles - he or she is only going to look for weights exceeding either the law (in that particular State) or the makers placard (on car and 'van), axle/tyre weight limits, and towbar capacity.

wbowner.....I think he reading that it isn’t included in the GVM based on the wording in the handbook

I’m with IndusD4, well I would include the TBW as part of GVM if that what’s stated on the placard.

Does the hand book state axle weights.....I have found you can exceed rear axle weight before exceeding GVM especially with big TBW.

Originally Posted by IndusD4

The 150kg you are quoting is not extra weight/mass. It is just the amount that is pushing down on the tow ball from the weight of the trailer. Not an extra 150kg you tow along.

With 150kg of weight on the tow bar your Gross Train Weight is still 3240+3500 (6740kg). With 350kg of weight on the tow ball, this is a reduced 3040+3500 (6540kg).


Hope that helps

Ron

Ron
Not sure .

if you have a TBM of 150kg then the GVM is 3240 as per placard.

If you don't have a TBM the GVM is still 3240

The difference is the payload, with a TBM of 150kg your payload must be reduced as in the end you can't exceed 3240 GVM in either case. This is the bit I can't get my head around.

Now if you have a 350kg TBM then it is really the same, you can't exceed GVM and 350kg has to come from the payload.

I am looking at it from the perspective of being pulled over and tested. They will go via what is on the placard. The stuff about inclusive 150kg is not mentioned there.

If they test the car GVM with the caravan attached, i.e. they weigh the car but not the van but van is still attached then the 150kg or 350kg will be reflected in this weighing and will go against the GVM.

I dont understand where this 150kg is hidden.

Richard

Ron
Sorry to keep at it but I find this still confusing. Can you answer these for me.


1) If my car without a van attached weighed 3240 (i.e. = GVM) and I attached a van with a TBM of 150kg what would the car now weigh. Would I be legal

2) Same situation with a 350kg TBM. Car by itself ways 3240kg. What would it weigh if I attached a TBM of 350kg.

Richard

Originally Posted by donh54

As I see it, the most confusion in this area comes from the talk of tow ball weights.

You cannot (legally) exceed any of; GVM, GCM (GTW), towball/bar capacity, or permitted axle weights as per the placard on the vehicle (unless there is a mod plate fitted.)

10% TBW is a furphy. It was put out as an easy to remember formula, but is not in any legal document I have ever seen. If you add 350kg to the towbar, it adds 350kg to the GVM. This is partially transferred to the front axle of the tow vehicle (particularly in the case of air suspension.)

The only way to be certain what you have in the way of weights is to load everything up as if you are going on a trip - including the amount of water you would normally carry in tanks, extra fuel cans, full fridges, etc. Then go to a weighbridge. Make sure the weighbridge has a flat access/exit apron.

Weigh the front axle of the tow vehicle, write this down. Drive the tow vehicle onto the weighbridge, so the caravan jockey wheel is just short of the weighing plate. Write the weight down. Unhook the 'van. Write the weight down. Hook the 'van back up, and drive completely onto the 'bridge. Write the weight down. As you drive off the bridge, you can unhook again, and weigh just the 'van. Write the weight down. Split weigh the 'van axles as you are leaving the weighbridge. Write the weights down.

Now, sit down with your beverage of choice, and by using the weights you have written down, you can work out what weights you have where, including the weight distribution of the van axles (more important in my view, than towball weight).

A Transport Department or Police Officer (or insurance adjuster) is not going to be interested in percentages, or weight transfer to/from axles - he or she is only going to look for weights exceeding either the law (in that particular State) or the makers placard (on car and 'van), axle/tyre weight limits, and towbar capacity.

I think what you are saying is what I think.

The reference to 150kg included in the GVM and 350kg is OK if you reduce the GVM is confusing and irrelevant (assuming TBM is not greater than 350kg)

It all comes down to what you weigh.

i.e. the car can't exceed GVM if a trailer is attached or not attached (any weight of the tow ball will appear in the car GVM weighing)
GCM can not be exceeded if the van is attached.
axle loads can not be exceeded

Richard
The confused one

ie
GC