Gross Vehicle Mass
Posted: Sun May 14, 2017 8:30 am
Most 563 owners are probably aware or their vehicles towing capacity and the rating of your towbar. Back in my first days on the "other" place, when it was happy, I contributed hopefully fruitfully to a discussion on towing and on GVM or Gross Vehicle Mass. I'm not an expert on the subject , nor much else for that matter, but it became apparent during that thread that many people don't understand GVM which is relative to towing large boats ( ie boats that are large relative to your vehicle). It's even relative to when you're loaded but not towing anything.
It came up recently again for me in regard to other matters not related to towing that a won't bore you with here. But I thought it might be of use to mention it here for those who may wish to know about this very important subject .
I'll use round figures for ease of explanation but put simply every car has a tare weight as stated on your rego . This is its unladen weight (with 10 litres of fuel) before you put even a paper clip in it....or yourself. In the end the tare is irrelevant it's the GVM that matters.
Your car has also a GVM which is the maximum weight allowable for that vehicle with everything on board . This includes you, your passengers, all your stuff and your BALL WEIGHT .
Don't bother my mate already made that joke
This is the down weight on your towball from your towed mass. Ideally this should be 10% of your total trailer weight, but this is not strictly mandated by regulations so there is some flexibility.
Now the really important thing is that many people seem not to understand GVM.
If you have a tare of say 1900kg and a GVM of 2500kg your payload is 600 kg. Sounds like a lot, dunn'it, hold that thought. There are many accessories available for vehicles now and adding them contributes to your payload. This is particularly an issue for 4wd and RVs . Add a steel bullbar , say 90kg, a towbar, say 40 to 50 kg, a roof rack, cargo barrier etc. ok now stick your outboard in the back of your wagon. You and your wife, well that's 140 kg for us, your kids or worse still your two mates who are front row forwards, a full esky and everyone's sailing bag. Now, let's get ridiculous. I did a quick check on stuff the other day when I was looking at this . I have two floor mats on the front of my falcon, they are heavy duty 4wd mats and alone weigh 5 kg.
So what you say 5 kg?. Well, I had a mate who was in a hot rod club years ago, and one night they were at the local hangout, one of the members truss roofed garage, where he kept his spares. Suddenly the ceiling caved in and deposited the stored contents on them all. The owners comment " but I only had light weight stuff up there". Moral...100 items weighing 2 kg weighs 200kg.
Get to know your normal loaded up weight of your vehicle and what spare capacity you have for towball download. Why ? Well if you exceed your GVM and have an accident you may be up a famous creek. Not only without a paddle but insurance cover as well. Not just your comprehensive insurance but also your third party green slip. Injure someone or worse and you might say goodbye to your house.
What prompted me to post this is an estimate I read that there are a high percentage of vehicles on the road regularly exceeding the gvm. Don't take my word on any of this but please do your own research. A weighbridge ticket locally costs $27. May be money well spent. Cheaper than losing your house anyway. I bought a towball scale from supercreep last time they were on special for about $50 . Spritzigs ball weight was 120kg with no outboard . Technically spot on.
I'm happy to go into the subject further particularly regarding trailer loading relevant to ball weight . As I said I'm not an expert . I spent another life in road safety so I often saw the end result of failures rather than the preventative end. There is much info on this matter on the net and it's worth reading all of it if you are unfamiliar with the subject.
You can google the state transport nasties in your state and then "car weights" or go to carsguide.com.au and "vehicle weights explained"
If you have any other first hand , professional or legal insights into this matter please add the info . I'm up for any additional knowledge on this subject I can get.
It came up recently again for me in regard to other matters not related to towing that a won't bore you with here. But I thought it might be of use to mention it here for those who may wish to know about this very important subject .
I'll use round figures for ease of explanation but put simply every car has a tare weight as stated on your rego . This is its unladen weight (with 10 litres of fuel) before you put even a paper clip in it....or yourself. In the end the tare is irrelevant it's the GVM that matters.
Your car has also a GVM which is the maximum weight allowable for that vehicle with everything on board . This includes you, your passengers, all your stuff and your BALL WEIGHT .
Don't bother my mate already made that joke
This is the down weight on your towball from your towed mass. Ideally this should be 10% of your total trailer weight, but this is not strictly mandated by regulations so there is some flexibility.
Now the really important thing is that many people seem not to understand GVM.
If you have a tare of say 1900kg and a GVM of 2500kg your payload is 600 kg. Sounds like a lot, dunn'it, hold that thought. There are many accessories available for vehicles now and adding them contributes to your payload. This is particularly an issue for 4wd and RVs . Add a steel bullbar , say 90kg, a towbar, say 40 to 50 kg, a roof rack, cargo barrier etc. ok now stick your outboard in the back of your wagon. You and your wife, well that's 140 kg for us, your kids or worse still your two mates who are front row forwards, a full esky and everyone's sailing bag. Now, let's get ridiculous. I did a quick check on stuff the other day when I was looking at this . I have two floor mats on the front of my falcon, they are heavy duty 4wd mats and alone weigh 5 kg.
So what you say 5 kg?. Well, I had a mate who was in a hot rod club years ago, and one night they were at the local hangout, one of the members truss roofed garage, where he kept his spares. Suddenly the ceiling caved in and deposited the stored contents on them all. The owners comment " but I only had light weight stuff up there". Moral...100 items weighing 2 kg weighs 200kg.
Get to know your normal loaded up weight of your vehicle and what spare capacity you have for towball download. Why ? Well if you exceed your GVM and have an accident you may be up a famous creek. Not only without a paddle but insurance cover as well. Not just your comprehensive insurance but also your third party green slip. Injure someone or worse and you might say goodbye to your house.
What prompted me to post this is an estimate I read that there are a high percentage of vehicles on the road regularly exceeding the gvm. Don't take my word on any of this but please do your own research. A weighbridge ticket locally costs $27. May be money well spent. Cheaper than losing your house anyway. I bought a towball scale from supercreep last time they were on special for about $50 . Spritzigs ball weight was 120kg with no outboard . Technically spot on.
I'm happy to go into the subject further particularly regarding trailer loading relevant to ball weight . As I said I'm not an expert . I spent another life in road safety so I often saw the end result of failures rather than the preventative end. There is much info on this matter on the net and it's worth reading all of it if you are unfamiliar with the subject.
You can google the state transport nasties in your state and then "car weights" or go to carsguide.com.au and "vehicle weights explained"
If you have any other first hand , professional or legal insights into this matter please add the info . I'm up for any additional knowledge on this subject I can get.