Having read a fair bit about the towing weight issue, GTM,ATM GVM, GCM etc... what I have not seen explained is, how is the maximum towing weight determined, I am not talking about the manufacturers limit.
i.e. is the max that can be towed the ATM of the towed van before hitching up, or is it the GTM once it is on the ball, or is it a case of as long as you do not exceed your GCM you are OK.
e.g. A Van has a ATM 3200kg unhitched behind a vehicle that has a max tow rating of 3000kg. With the van hitched and tow ball weight at 300kg, now the van is GTM 2900kg.
Once it is hitched up and with the tow vehicle loaded with stuff (as we do) and now the combination at it's GCM of 6000kg is this still legal ?
The manufacturers put out their figures but do not state, that I have seen, if this includes or excludes the ball weight of the towed van, so is it the ATM or GTM that is used as the max tow weight.
No, I do not intend to tow at those weights, just asking for clarification as it is becoming quite an issue.
-- Edited by Rod Mac on Saturday 15th of December 2018 06:58:31 AM
TheHeaths said
07:05 AM Dec 15, 2018
Rod.
The ATM is the maximum allowable weight of the van, set by the van maker, unhitched from the vehicle.
The GTM is the maximum allowable weight on the wheels, set by the van maker, when hitched to the vehicle.
The GTM and ATM are both ratings, NOT actual weights.
In your example, where the van actually weighs 3200 kg unhitched and the vehicle has a maximum tow weight of 3000 kg, you cannot tow that van at that loaded rate. The ATM decides the tow weight, not the GTM as you have shown in your example.
The maximum you can tow is either the ATM of the van (if below 3000 kg), limited by the vans rating, or the allowable tow weight (in this case 3000 kg) allowed by the car maker.
At the same time, the ball weight must be below that allowed by the car maker, and the total with of the car and van combined must be at or below the GCM, if set by the car maker.
That is my understanding of the situation. I am certain someone will correct me if that is not correct.
-- Edited by TheHeaths on Saturday 15th of December 2018 07:06:52 AM
Whenarewethere said
08:41 AM Dec 15, 2018
& if your weight on the towball is at the maximum the car might be de-rated as well.
Not only will you have next to no capacity in the van & there is little to start with anyway, you will have next to no capacity in the car. Add 2 people & a couple of spare undies & you are at the limit.
My car can have up to 350 kg on the towball but with 150 kg left, less the mass of the towbar itself, I could not carry a second passenger! Mind you I could say to other you will have to say at home!
Luckily I do not tow! Recently I weighed every single item we put in the car & had heart failure!
rockylizard said
10:00 AM Dec 15, 2018
Rod Mac wrote:
SNIP~~~ is the max that can be towed the ATM of the towed van before hitching up, or is it the GTM once it is on the ball, or is it a case of as long as you do not exceed your GCM you are OK.
Gday...
Firstly, you have the terms reversed -
ATM (aggregate trailer mass) This is the tare mass of your caravan plus its maximum payload. Its the maximum your caravan is allowed to weigh in transit ( ie when hitched to the vehicle). This is a rating set by the manufacturer and cannot be exceeded.
GTM (gross trailer mass) This is the maximum weight of the loaded caravan that can be supported by its wheels, not counting the portion supported by the car when hitched or jockey wheel when parked. This rating is set by the manufacturer and cannot be exceeded.
Despite the above, I have not been able to find, despite too much time researching, whether it is ATM or GTM that is the maximum that a vehicle can tow.
As you have asked, if the vehicle's plate says maximum braked towing capacity is 3,000Kg just what is the maximum it can tow - a van with with an ATM of 3,000Kg or a GTM of 2,700Kg.
For what it's worth most discussion is that the maximum braked towing capability of a vehicle is the ATM of the van (someone will yell at me if that is not correct).
Interestingly, should a rig be pulled over for weighing to confirm compliance by authorities they are quite likely to weigh the steer axle, the drive axle, the trailer axle/s and each will need to be compliant with the vehicle's plate - or rating. Authorities may combine those axle weights to determine GVM, ATM and GCM.
Hope that helps in some way.
cheers - John
Whenarewethere said
12:31 PM Dec 15, 2018
A bit more here:
'Why most modern UTE tow ratings are bulls#!t' https//www.club4x4.com.au/modern-ute-tow-ratings-bullst/
LLD said
01:02 PM Dec 15, 2018
One fatal mistake that I've seen nomads do is to load their van & tug because they can. Every cubby-hole in the van is full. Some work on volume, not weight. There is stuff loaded (both van & ute) that will never be used. Was guilty of that myself back in the 1980s when I first started vanning. We pared things down for a recent 10,000km trip around the West Coast. Still took stuff we never used and were never going to use.There was stuff that we never used but it will be going again. I'm in the process of even removing more for our big trip(s) next year.
Packing for a 10 week trip is quite different than packing for a 10 day stay in the one spot with no facilities.
FYI.
The Ranger XLT 4dr 4wd 3.2L weighed in at 2660kg. Add about 250kg to that for self, wife and odds and ends thrown in after the weigh-in.
The Jurgens Sungazer weighed in at 1540kg.
Rod Mac said
01:16 PM Dec 15, 2018
Hi John, an herein lies a problem.
On the RACQ site the ATM is classed as max the van can weigh when not coupled to a tow vehicle as rated by the manufacturer.
However the AL-KO site states ATM is the maximum weight allowed when in transit which then can be taken as being on the ball ?
The RACQ site does also state in one sentence that the max towing weight a vehicle is allowed to tow is based on the ATM, found that little gem with a bit of digging this morning, which answers my question that I asked in my first post/query, so that is sorted. i.e.Tow vehicle max towing weight is the van ATM
However it now opens a can of worms as to what is the correct way of looking at ATM and GTM.
I believe ATM is total weight allowed unhitched and about to be in put in transit, which is why a weighbridge will weigh a van off the ball and then weigh the van on the ball.
What is obvious is that ATM and GTM are both maximum weights as rated by the manufacturer but discussion can go on for a bit as to coupled or uncoupled.
Happy to be corrected but it does show some confusion exists.
Whenarewethere said
01:25 PM Dec 15, 2018
A list of everything added to my car & I have missed a few things, frightening stuff, & I don't even have a bull bar to add to the weight!
My car can have up to 350 kg on the towball but with 150 kg left, less the mass of the towbar itself, I could not carry a second passenger! Mind you I could say to other you will have to say at home!
If that's the Freelander 2, I thought it had max noseweight of 150kg?
To put it in simple terms and to answer the original question.
The ATM is the weight that must be used.
However, the one thing in the example you have given which could vary is the vans payload.
For arguments sake lets say the van in the example has a tare of 2600kgs and the ATM is the 3200kgs as given. This means you have a payload of 600kgs you can put in the van. If you only loaded a maximum of 400kgs into the van then the actual weight of the van if placed on the scales would be 3000kgs so in theory you could tow the van with the vehicle in the example. The ATM relates to the maximum weight the van can weigh complete with payload.
The practicality though is a different thing. I personally would not recommend putting a van that weighed in at the vehicles maximum tow capacity on the back. I would be looking to give myself about 500kgs safety margin.
Whenarewethere said
07:14 PM Dec 15, 2018
Mamil wrote:
Whenarewethere wrote:
My car can have up to 350 kg on the towball but with 150 kg left, less the mass of the towbar itself, I could not carry a second passenger! Mind you I could say to other you will have to say at home!
If that's the Freelander 2, I thought it had max noseweight of 150kg?
Yes you are right at 150 kg. But it can increased to 250 kg but you have to reduce the payload by 100 kg for other countries. But for Australia it can be increased to 350 kg by decreasing payload accordingly.
Must be the only small car ever made that has 350 kg tow ball weight. But there is not a lot left for anything else! But it is good to know the car is built well.
Also the towing weights are for on road. Not for off road! Which will be similar to all the other car owners who think they can tow 3500 kg off-road. No you cannot!
Having said that we have some shocking gazetted roads, which are probably worse than some off-road terrain, ie especially chronic road corrugations.
montie said
10:12 AM Dec 16, 2018
The measured weight of the unhitched van must not legally exceed the ATM rating as stamped on the compliance plate. Neither can that measured weight exceed the towing capacity rating of the tug.
A sensible approach should be that the vehicle towing capacity should at least equal and preferably exceed the van's rated ATM.
In the event that the ATM rating exceeds the towing capacity (not recommended) then you can only load the van to the rated tow capacity.
-- Edited by montie on Sunday 16th of December 2018 10:14:14 AM
Whenarewethere said
11:16 AM Dec 16, 2018
It is all a bit complex when one is getting closer to the limit. Then if you have got the maximum on the towball then the payload of the car needs to be reduced a lot. & How much is on each axle.
You have X weight on the towball but you get a leaverage effect, say 1.4 times, shifting some weight from the front axle to the rear axle. & There is probably too much over the rear axle with maximum towball weight & leaverage together with a fridge in the back!
In my handbook they say the the front & rear axles can take X & Y loads, but what is on each axle when I get the car from the showroom. I should not have to find a weighbridge for this.
I always try to pack the weight forward where possible to keep things as central as possible. Luckily I'm not towing, but it is still too complex to easily calculate for a car only let alone a caravan as well.
Having read a fair bit about the towing weight issue, GTM,ATM GVM, GCM etc... what I have not seen explained is, how is the maximum towing weight determined, I am not talking about the manufacturers limit.
i.e. is the max that can be towed the ATM of the towed van before hitching up, or is it the GTM once it is on the ball, or is it a case of as long as you do not exceed your GCM you are OK.
e.g. A Van has a ATM 3200kg unhitched behind a vehicle that has a max tow rating of 3000kg. With the van hitched and tow ball weight at 300kg, now the van is GTM 2900kg.
Once it is hitched up and with the tow vehicle loaded with stuff (as we do) and now the combination at it's GCM of 6000kg is this still legal ?
The manufacturers put out their figures but do not state, that I have seen, if this includes or excludes the ball weight of the towed van, so is it the ATM or GTM that is used as the max tow weight.
No, I do not intend to tow at those weights, just asking for clarification as it is becoming quite an issue.
-- Edited by Rod Mac on Saturday 15th of December 2018 06:58:31 AM
Rod.
The ATM is the maximum allowable weight of the van, set by the van maker, unhitched from the vehicle.
The GTM is the maximum allowable weight on the wheels, set by the van maker, when hitched to the vehicle.
The GTM and ATM are both ratings, NOT actual weights.
In your example, where the van actually weighs 3200 kg unhitched and the vehicle has a maximum tow weight of 3000 kg, you cannot tow that van at that loaded rate. The ATM decides the tow weight, not the GTM as you have shown in your example.
The maximum you can tow is either the ATM of the van (if below 3000 kg), limited by the vans rating, or the allowable tow weight (in this case 3000 kg) allowed by the car maker.
At the same time, the ball weight must be below that allowed by the car maker, and the total with of the car and van combined must be at or below the GCM, if set by the car maker.
That is my understanding of the situation. I am certain someone will correct me if that is not correct.
-- Edited by TheHeaths on Saturday 15th of December 2018 07:06:52 AM
& if your weight on the towball is at the maximum the car might be de-rated as well.
Not only will you have next to no capacity in the van & there is little to start with anyway, you will have next to no capacity in the car. Add 2 people & a couple of spare undies & you are at the limit.
My car can have up to 350 kg on the towball but with 150 kg left, less the mass of the towbar itself, I could not carry a second passenger! Mind you I could say to other you will have to say at home!
Luckily I do not tow! Recently I weighed every single item we put in the car & had heart failure!
Gday...
Firstly, you have the terms reversed -
ATM (aggregate trailer mass)
This is the tare mass of your caravan plus its maximum payload. Its the maximum your caravan is allowed to weigh in transit ( ie when hitched to the vehicle). This is a rating set by the manufacturer and cannot be exceeded.
GTM (gross trailer mass)
This is the maximum weight of the loaded caravan that can be supported by its wheels, not counting the portion supported by the car when hitched or jockey wheel when parked. This rating is set by the manufacturer and cannot be exceeded.
http://www.withoutahitch.com.au/caravan/understanding-caravan-towing-capacity/
Despite the above, I have not been able to find, despite too much time researching, whether it is ATM or GTM that is the maximum that a vehicle can tow.
As you have asked, if the vehicle's plate says maximum braked towing capacity is 3,000Kg just what is the maximum it can tow - a van with with an ATM of 3,000Kg or a GTM of 2,700Kg.
For what it's worth most discussion is that the maximum braked towing capability of a vehicle is the ATM of the van (someone will yell at me if that is not correct).
Interestingly, should a rig be pulled over for weighing to confirm compliance by authorities they are quite likely to weigh the steer axle, the drive axle, the trailer axle/s and each will need to be compliant with the vehicle's plate - or rating. Authorities may combine those axle weights to determine GVM, ATM and GCM.
Hope that helps in some way.
cheers - John
A bit more here:
'Why most modern UTE tow ratings are bulls#!t' https//www.club4x4.com.au/modern-ute-tow-ratings-bullst/
Packing for a 10 week trip is quite different than packing for a 10 day stay in the one spot with no facilities.
FYI.
The Ranger XLT 4dr 4wd 3.2L weighed in at 2660kg. Add about 250kg to that for self, wife and odds and ends thrown in after the weigh-in.
The Jurgens Sungazer weighed in at 1540kg.
Hi John, an herein lies a problem.
On the RACQ site the ATM is classed as max the van can weigh when not coupled to a tow vehicle as rated by the manufacturer.
However the AL-KO site states ATM is the maximum weight allowed when in transit which then can be taken as being on the ball ?
The RACQ site does also state in one sentence that the max towing weight a vehicle is allowed to tow is based on the ATM, found that little gem with a bit of digging this morning, which answers my question that I asked in my first post/query, so that is sorted. i.e.Tow vehicle max towing weight is the van ATM
However it now opens a can of worms as to what is the correct way of looking at ATM and GTM.
I believe ATM is total weight allowed unhitched and about to be in put in transit, which is why a weighbridge will weigh a van off the ball and then weigh the van on the ball.
What is obvious is that ATM and GTM are both maximum weights as rated by the manufacturer but discussion can go on for a bit as to coupled or uncoupled.
Happy to be corrected but it does show some confusion exists.
A list of everything added to my car & I have missed a few things, frightening stuff, & I don't even have a bull bar to add to the weight!
https://thegreynomads.activeboard.com/t65110614/towing-weights-again/
If that's the Freelander 2, I thought it had max noseweight of 150kg?
Yes you are right at 150 kg. But it can increased to 250 kg but you have to reduce the payload by 100 kg for other countries. But for Australia it can be increased to 350 kg by decreasing payload accordingly.
Must be the only small car ever made that has 350 kg tow ball weight. But there is not a lot left for anything else! But it is good to know the car is built well.
Also the towing weights are for on road. Not for off road! Which will be similar to all the other car owners who think they can tow 3500 kg off-road. No you cannot!
Having said that we have some shocking gazetted roads, which are probably worse than some off-road terrain, ie especially chronic road corrugations.
The measured weight of the unhitched van must not legally exceed the ATM rating as stamped on the compliance plate. Neither can that measured weight exceed the towing capacity rating of the tug.
A sensible approach should be that the vehicle towing capacity should at least equal and preferably exceed the van's rated ATM.
In the event that the ATM rating exceeds the towing capacity (not recommended) then you can only load the van to the rated tow capacity.
-- Edited by montie on Sunday 16th of December 2018 10:14:14 AM
It is all a bit complex when one is getting closer to the limit. Then if you have got the maximum on the towball then the payload of the car needs to be reduced a lot. & How much is on each axle.
You have X weight on the towball but you get a leaverage effect, say 1.4 times, shifting some weight from the front axle to the rear axle. & There is probably too much over the rear axle with maximum towball weight & leaverage together with a fridge in the back!
In my handbook they say the the front & rear axles can take X & Y loads, but what is on each axle when I get the car from the showroom. I should not have to find a weighbridge for this.
I always try to pack the weight forward where possible to keep things as central as possible. Luckily I'm not towing, but it is still too complex to easily calculate for a car only let alone a caravan as well.