Towing capacity vs weight

Submitted: Monday, Aug 27, 2012 at 12:06
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Hi towing-gurus!

I'm confused about something. I can see there's a lot of love for Prados, Landcruisers & other big tow tugs on the forums, but in researching a lighter tow-tugs I've gotten curious about something.

A general rule with towing is that you don't tow more than your vehicle weighs, is that right? So with a vehicle that weighs say 1560kg, but with a rating tow of 1800kg, you wouldn't tow more than that 1560kg?

So, a Mazda CX-5, with a kerb weight (auto) of 1475kg, but with a rated tow of 1800kg, you still stay under the 1475kg?

But then a Mazda BT-50 dual cab, with a kerb weight of only 1964kg, can tow a whopping 3350kg! Are you *supposed* to fill the tub of that BT-50 with another tonne to bring the towing allowance up?

(Make fun of me, but I'm researching a 2nd hand Volvo S80/V70, tow rating 1800kg, and a new CX5 which also tows 1800kg. Not many of you like either of these (in fact, I'd hesitate to say ANYONE likes towing with a Volvo, or at least anything less than a XC90) for parts availability etc. I'm not intending to drive through the middle of the outback with either of these, just mostly the coast roads to start with I'd say, with a Bailey.)

So can someone explain to me the weight of the car vs the weight of allowed towing? I'm sure it's a safety thing (duh, if your caravan weighs more than your car, it'll pull the car around, right?) but the BT-50's throwing me out.

Thank you in advance.
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Reply By: Member - John G- Monday, Aug 27, 2012 at 12:43

Monday, Aug 27, 2012 at 12:43
G'day Lizcantow

See www.campertrailers.org under Tech Tips / Australian Towing Regulations

Cheers
John
AnswerID: 493708

Follow Up By: LizCanTow - Monday, Aug 27, 2012 at 14:17

Monday, Aug 27, 2012 at 14:17
Thank you John for your direction. I found this site: http://www.campertrailers.org/balancing_act.htm where it speaks of the law regarding towing.
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Reply By: Member - Wamuranman - Monday, Aug 27, 2012 at 12:50

Monday, Aug 27, 2012 at 12:50
Hi Liz,

You have probably opened up a can of worms here as there are differing views on this.

Here is what my opinion is.
The specified total trailer weight of a vehicle is the maximum you can tow in “good conditions”. With my Landcruiser this is 3500 Kg. However I choose NOT to tow at the limit of my vehicle for long distances. I have a self imposed limit of about 85% of the vehicles maximum (about 3000 kg). In my view this gives me a “buffer” of safety should I strike adverse road conditions unexpectedly (eg on recent trip came across cattle on road after rounding a bend and had to brake to a standstill suddenly).

Yes you can legally tow a trailer greater weight than your tow vehicle. The maximum loaded weight of my Landcruiser is 3300kg. So I could legally tow a trailer 200kg heavier than my tow vehicle. However I CHOOSE not to. I am of the view that it is safer to have the tow vehicle heavier than the trailer. Toyota recommend that if the trailer is heavier than the tow vehicle a sway control device should be used.
Generally you have very few kilometres of road that to me would be classified as “good conditions”….much of our outback roads have dips, broken edges, potholes, narrow bitumen etc as well as the possibility of wet conditions. So in my personal view it is dangerous to tow to the vehicles maximum capacity for long distances (I am happy to tow a 3500kg boat a few kms to the local boat ramp).

When ordering a new off road caravan recently we specifically wanted one less than 3000kg ATM. It came in at about 2750kg. But this was a self imposed limit by choice. Over the past few years in our travels we have seen 3 jack-knifed van accidents. They do happen. My view is you can reduce the risk of this happening by towing less weight than the manufacturers specified maximum and by keeping the tow vehicle heavier than the trailer.

Cheers




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Follow Up By: LizCanTow - Monday, Aug 27, 2012 at 14:31

Monday, Aug 27, 2012 at 14:31
Thank you for your reply Wamuranman. No wonder I'm confused if it's a can of worms!

(ie, what I'm looking at is a caravan with a TARE of 1400kg, a ATM of 1700kg & a max tow rating of 1800kg. We'd be wanting to keep it more like 1600kg to be closer to an 85% ratio, which is a light-load!)
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Follow Up By: Members - Bow & Nan - Tuesday, Aug 28, 2012 at 07:45

Tuesday, Aug 28, 2012 at 07:45
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Follow Up By: LizCanTow - Tuesday, Aug 28, 2012 at 09:09

Tuesday, Aug 28, 2012 at 09:09
HAhahAHAHA Nice one!!!! :D

Thanks for posting it Bow & Nan.
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Reply By: Member - Tony V (NSW) - Monday, Aug 27, 2012 at 13:54

Monday, Aug 27, 2012 at 13:54
Liz,

No need to make fun as this subject is a can of worms.

My understanding is that a vehicle is designed with components that will enable it to work with a Gross Combined Mass (GCM)

So there is 3 measurements that need to be followed. Gross combined Mass (GCM) - Gross Vehicle Mass (GVM) and Braked towing capacity.

So using my 100 series

GCM = 6680kg total (This can never change even with a GVM upgrade). Vehicle and towed mass.

Gross Vehicle Mass (GVM) is made up of Kerb weight (2413 kg) and Payload capacity (767 kg). So GVM is 3180kg.

GCM is made up by adding GVM = 3180 kg and braked towing capacity 3500kg
________________________________________________________

So depending on vehicle fit out (GXL 767 kg to Sahara 516 kg) the payload will change.

A GVM upgrade, in my case up by 500kg - 3180 to 3680 my towing capability is reduced by 500 kg to fit within the GCM.

All that said, I would limit my towing to 75% of the tow vehicle and not run at maximum capacity........... but then again a B-Double a prime mover weighs a fraction of what it pulls and stops, same as a road train.


(By the way, the BT-50 is an anomaly as the quoted figures do not seem to add up!)
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Follow Up By: LizCanTow - Monday, Aug 27, 2012 at 14:15

Monday, Aug 27, 2012 at 14:15
Tony,

Not making fun, I assure you. I'm honestly trying to wrap my head around this issue!! :) (I should point out I was sure someone was going to make fun of me for considering a Volvo sedan as a tow tug!)

And THANK YOU for your BTW comment about the BT-50. Doesn't make sense to me either. This is where I got the figures for the BT-50 from: http://www.mazda.com.au/vehicles/bt-50/specifications

Looking at the 4x2, dual-cab, auto: it states the Kerb weight (1964kg) & payload capacity (1236kg) = the GVM (3200kg). But then they state the allowed tow is 3350kg & the GCM is 5950kg. Add the GVM & Tow is 6650kg! definitely doesn't add up. I would say one would have to limit the payload capacity & towing to get the GCM right.

I'm still confused about the idea that one isn't supposed to tow more than the vehicle weighs, since the BT-50 weighs in some 1386kg less than it's towing capability. (hense, my confusion)

Thank you for your reply :)
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Follow Up By: pop2jocem - Monday, Aug 27, 2012 at 15:24

Monday, Aug 27, 2012 at 15:24
Hi Liz,

Firstly I'm sure most of us took your statement about towing with a Volvo as the light hearted attempt at humour you intended.
All vehicle manufacturers have a maximum towing capacity quoted as required by law and as such in the unfortunate occurrence of an accident your compliance with this limit gives your insurance company and any relevant traffic authority less ammunition to cause you any more grief than you already have.
As others have stated a prime mover, tractor or what ever you call them towing a trailer and possibly multi trailers have certain ratings far in excess of the weight of the prime mover. In this context please consider the following. You have had the misfortune to suffer a failure of your vehicle which has left you stranded on the highway just around a blind bend with steep shoulders prohibiting any approaching traffis steering around you and therefore they have to brake to avoid a collision.
What would you rather have come around that bend? A road train at or close to its maximum legal load (maybe 150 or so tonnes) or a car and caravan at or close to maximum legal weight both doing 100 kph. This is assuming that the driver of the road train is concentrating on the job, not talking on the 2 way to his mate behind him or popping a pill or two and the car/van driver not having a little nana nap while going along and both vehicles having a braking system that is up to scratch. To take this one step further would you rather the car/caravan weight be in favour of the tow vehicle or whatever he is dragging?

Just a thought

Cheers
Pop
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Follow Up By: LizCanTow - Monday, Aug 27, 2012 at 15:31

Monday, Aug 27, 2012 at 15:31
Hi Pop,

No really, a Volvo can tow! ;-) (in all seriousness.)

So, as far as an accident is concerned, one's caravan/trailer should be within the vehicles maximum towing capacity. Right. So a car rated for 1800kg (with a similarly rated tow ball) towing a caravan weighing in (loaded up) at 1600kg, (88%) is fine. As far as the police & insurance company is concerned.

I'd want to be no where NEAR my vehicle on that blind bend with those two differing loads approaching thanksverymuch! I'd be climbing the cliff! Obviously I'd want the car to be in favour rather than the caravan.

Thank you for your reply. :)
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Follow Up By: pop2jocem - Monday, Aug 27, 2012 at 16:29

Monday, Aug 27, 2012 at 16:29
No worries Liz, just kidding about the Volvo (;-))
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Follow Up By: LizCanTow - Monday, Aug 27, 2012 at 16:42

Monday, Aug 27, 2012 at 16:42
Haha Pop you're funny :D

I'm a bit puzzled why people don't think Volvo's are good for tows. Sure, not for going into the outback towing a real heavy caravan (unless it's an XC90 I guess!) but for coastal trips? Where you pop on the caravan to go up to the Central coast of NSW from VIC? I thought it'd be OK :) Sure, they are a lighter weight tow, but so is a Subaru Outback, or a CX5.

(Can you tell I'm a Volvo driver? I have a beloved 240GL which I'm sure was able to tow something at some point but has only ever been used to tow a trailer as long as I've had it!)
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Follow Up By: pop2jocem - Monday, Aug 27, 2012 at 19:35

Monday, Aug 27, 2012 at 19:35
Hey Liz,
Now don't go telling anyone else but...




when I was a young lad in my late teens.....yeah yeah I know..... I thought everyone rode horses back then...lol I wanted to buy a 144 for no other reason than all my mates went on and on about VOLVOS and their drivers. Not sure if you know but apparently Volvo is latin for I Roll.

Cheers
Pop
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Follow Up By: LizCanTow - Tuesday, Aug 28, 2012 at 09:38

Tuesday, Aug 28, 2012 at 09:38
Wooooooo Pop don't let anyone see you admit that!! :D

Volvo is indeed derived from the Latin Volvere, and does mean I Roll :D

And since I'm used to my 240gl sucking up 15L/100kms (on mostly freeway driving!), I reckon I'm ready for the fuel suckage of towing a caravan! *laugh*

Liz
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Reply By: mountainman - Monday, Aug 27, 2012 at 15:30

Monday, Aug 27, 2012 at 15:30
GCM can BE CHANGED.

Your wrong on that.
an 80 series can be upped from 2980 gvm to 3350 gvm, and the GCM was upgraded too.
the 80 series was 2500kg rated upped to 3500kg towing capacity.
been done with a canberra engineer.

soo what someone says isnt always the bible.
find out for yourself with the local authorities than taking someones word for it.


AnswerID: 493718

Follow Up By: LizCanTow - Monday, Aug 27, 2012 at 15:42

Monday, Aug 27, 2012 at 15:42
So mountainman, would you recommend towing something that weighs more than your car?

And should you pay attention to the GVM figure rather than the kerb weight? (Some specs only give a kerb weight rather than a GVM...)

Thank you for your reply :)
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Follow Up By: Member - Tony V (NSW) - Tuesday, Aug 28, 2012 at 12:43

Tuesday, Aug 28, 2012 at 12:43
Thanks Mountainman,

I should have been more specific,

With the exception of the 80 Series GVM is a Manufactures (Toyota) upgrade, with a GCM change from 5460 to 6680 kg.

Many 80 series can have this completed after being inspected by a certified engineer as to the vehicles condition, they can authorise a change to the compliance plate and registration papers, without any modification to the vehicle.

80 series upgrade on this site

"soo what someone says isnt always the bible.
find out for yourself with the local authorities than taking someones word for it."

I would agree with that :)
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Reply By: mountainman - Monday, Aug 27, 2012 at 17:55

Monday, Aug 27, 2012 at 17:55
yes i would.
i would make sure their is a decent load on the rear axle of the vehicle to tow the max capacity, it helps in the wet!!

and especialy with any suspension lift, i would definatly recommend getting the brakes checked to see that the LPSV, load proportioning s valve is working when you carry some weight in the rear.

i recently was fully loaded, over 3tonne, in an industrial area, driving about 30k' an hour and had to brake, road was recently dry for some time, and it rained, soo super greasy, the fronts locked up as they do, and i kept them locked up, as usualy im going quicker, i slid about 10mtrs overshoot the t intersection, and came to a stop finaly.
realised the rear brakes never came on!!
soo got around to the LPSV and raised it about 20mm, off the diff.
took it down a dirt road, doing 40 to 50, braked hard, fronts locked, then unlocked via my foot pressure on the pedal, and the rears worked a treat.

no worries towing a full van, just make sure their is some weight on the vehicle to pull it up.
or cross winds to throw the vehicle around, or simply do the safest thing and reduce speed.
AnswerID: 493734

Follow Up By: LizCanTow - Tuesday, Aug 28, 2012 at 09:44

Tuesday, Aug 28, 2012 at 09:44
Thanks for sharing your recent hair-raising example mountainman!!

I was just thinking that putting weight in the boot (ie, extra things) might help with (a) making the vehicle heavier (in thinking about kerbweight I had completely forgotten that when there's two people & a dog in the car the car is automatically 150kg heavier!) and (b) steadying the tow.

Thanks for your reply!
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Reply By: Member - Anthony W Adelaide - Monday, Aug 27, 2012 at 18:29

Monday, Aug 27, 2012 at 18:29
Hi Lizcantow,

With all those numbers I am starting to get a head ache. Manufacturers are only interested in selling cars so their ratings tend to be a bit optomistic at times I think.

I reckon Wamuranman is spot on with his formula.

IMHO, common sense and the laws of physics say that the tug must be 15-20% heavier than the van/trailer to maintain control in all but the worst conditions.

What is the kerb weight of the volvo's?
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Follow Up By: LizCanTow - Tuesday, Aug 28, 2012 at 09:35

Tuesday, Aug 28, 2012 at 09:35
At least I'm not the only one with a headache! It's very confusing for a new-to-caravan-towing person to try and match the right car (for the right price) to the right caravan. Especially when you don't want a big Landcruiser/Prado/Patrol etc.

Kerb weight for:
2003 Volvo S80: 1637kg, tows 1800kg.
2003 Volvo V70: 1528kg, tows 1800kg
2003 Volvo XC70: 1655kg, tows 1800kg
(I'll stop here, since there's a pattern going on, and they're all generally like this.)

(2012 Mazda CX-5: 1475kg, tows 1800kg)
(2012 Mazda BT-50: 1964kg, tows 3350kg.)

Of course, I'd like to be able to find payload figures and GVM's on these cars, which seems impossible (except for the BT-50, where there's a bazillion figures, half of which don't quite add up) because some Volvo's state (the new V60 for example I think) that they'll tow 1800kg, but with nothing in the boot. And one would think that traveling around would see you with stuff In The Boot, which would then increase the weight of the car as well. (Which I wouldn't hesitate to say is a bad way of increasing the ratio of car weight to caravan weight.)

The caravan we want is 1400kg TARE and loads up to 1700kg. (we wouldn't want to load it up to be honest. We'd be looking at keeping it aorund 1600kg I would think.)
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Reply By: olcoolone - Tuesday, Aug 28, 2012 at 09:12

Tuesday, Aug 28, 2012 at 09:12
Classic example of thinking to much about something that is not needed to be known and then trying to figure out the calculations of how the many factory engineers came to their conclusion......

All vehicles have advertised maximum weights for the vehicle by it's self and if towing.

If you exceed these weights your overloaded and if you stay under these weights your safe.

All you have to ask is "can my vehicle carry and tow this weight...... it's going to be yes or no..... there is no maybe's or?????....... it's yes or no.

Maybe the vehicle manufactures should look on the forums for there next lot of engineers......

There are many things that come into the equation.... Axle loadings, axle capacities, suspension, chassis, brakes, drive train, engine cooling and many more....
AnswerID: 493769

Follow Up By: LizCanTow - Tuesday, Aug 28, 2012 at 09:42

Tuesday, Aug 28, 2012 at 09:42
olcoolone, THANK YOU for your straight forward words. I'm always overthinking things (buying groceries can be a nightmare for example :D) and making such a big investment as the right car with/for the right caravan, is one of those things that's going to make me overthink.

Of course the one thing we're not taking into consideration (well I haven't been until this moment) is two people (& a dog) sitting in the car whilst it's being towed! Ta da - car is 150kg heavier, which takes a lot of the car payload figures right up to what they can tow.

\0/

Thanks for your reply :)
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Follow Up By: pop2jocem - Tuesday, Aug 28, 2012 at 18:00

Tuesday, Aug 28, 2012 at 18:00
Hey olcoolone,

Where did you get the idea that the vehicle conception happens in the engineering department of any manufacturer. I think the sales and market research mobs have a fair bit to do with what it is going to look like and who it has to compete against.
Then the engineering crew get to make it all fit.

Cheers
Pop
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Reply By: Member - Chris & Debbie (QLD) - Tuesday, Aug 28, 2012 at 09:38

Tuesday, Aug 28, 2012 at 09:38
I don't think you have opened a can of worms at all. Your main query was about the general rule of not towing more weight than the tow vehicle.

To answer this questiion, there is no such rule.

People have different ideas on what weight you can or can't tow but it still comes down to what the manufacturer states you can tow legally not some general rule, but do agree that you need to allow for road conditions etc.
Chris
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Follow Up By: LizCanTow - Tuesday, Aug 28, 2012 at 09:46

Tuesday, Aug 28, 2012 at 09:46
Yes, that was my original question ;-) Thanks for noticing, & answering it!
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