What is a safe towing weight? FAO Marsh Harrier

[ProfJohnL]

In another thread you have posted a question:

The more I read the more I get confused concerning a safe weight...

I know that my

kerb weight 1,810kg
tow 1,500kg
Nose on Hitch 75kg

I'm buying an Elddis affinity 540. unladen 1298kg
MTPLM 1450kg

So assuming the max weight for the caravan is less than my cars towing weight, I'm pretty safe with the towing.

So on a quick calculations and a simple theory, so if I keep my caravan weight within its limits, and ensure than the nose weight is 75kg.. I'm towing safely

My tow car is an Mitabishi outlander PHEV, Which on demo's it's towing a 17ft Swift Sprite which is slightly heavier than the Elddis.

It used to tow my old Elddis Avante 520 without problems.

I have copied it and created a new thread, to avoid futher pollution of a thread that Parksey has commented on.

I note from your post that you have experienced caravanning before, so you are not new to it, and hopefully you will have gained some experience and wold be able to spot the some of teh early signs of when an outfit may be about to become unstable.

With that in mind your choice of car and caravan on paper looks OK, and has a towing ratio of 97% which is inline with the industry advice.

I would make two comments though. The first is about safety. No one can tell you whether your proposed outfit is "safe" Safety is far more about driving style and habits that any weight ratio. It is vitally important that both the car and the caravan are properly maintained and the correct tyre pressures etc are set. Loading is important and ill offer some views on that in the next paragraph, but the single most important factor that affects safety is speed. Every outfit is stable when stationary, its only when the speed is increased that the chances of instability also increase. If you begin to detect instability slow down, .and at the earliest safe opportunity pull over and reassess your loading.

With regards to loading, its important to keep moments of inertia to a minimum - that's engineering for keeping heavy items low down and as near the axle of the caravan as possible, however yo do need to create some nose load, and that is generated by having the caravan loaded so its always pushes it nose down. How much nose load is also not a specifically definable figure, but you must be mindful of the mechanical limits for the noseload set by both the car and the caravan manufacturer. IF there is a difference between the car and caravans specification for nose load always use the lower figure as your absolute limit. It isn't always necessary to use the scope of a nose load limit but it is proven that more is better than less.

 

[Marsh Harrier]

Thanks Prof

I do find working it all out a bit confuddling, More so checking my Vin plate if I do a straight working off this...
MAM 2390kg
Gross Train weight 3920kg

Working from this alone, would give me a towing weight of 1530kg

But logbook says 1500kg is the max has advised by Mitsubishi (Outlander PHEV)

I was taught reversing the caravan many years ago, by my brother in law, Lorry driver and caravaner. Alongside how to load and check the nose weight! Also visual checking the line of the caravan hooked to the car..

But I have actually decided to get myself a proper Nose Weight Gauge, so I can check out my nose weight due to being 75kg..

I've never had issue with the caravan being towed apart from having to carryout an emergency stop at 40mph, I saw the Fire Engine pulling up to the junction ahead of me to my left. Then as I got near, they decided to put their blues and two's on and pull out of the Junction. Leaving me hitting my breaks as the fear of jack knifing the caravan into the boot of the car where my two dogs were... Still don't know how I managed to stop my car and caravan keeping it straight.

I've had the trailer tent snake on my on the A303, hit a pot hole that throw it into a snake, so just lifted my foot of the accelerator and allowed it to sort itself out...

 

[ProfJohnL]

On the "What is my cars's towing weight limit? thread RogerL offerd this point.

It's a fallacy to think you can assess stability in normal driving as almost every outfit is stable then - the real test is when you have to manoeuvre sharply, that's when you find out how stable your outfit is.

To a large extent I agree. Often its the sudden dramatic inputs that can will exceed the cars margin of control, and as such gentle driving is going to be less eventful than trying to emulate a formula 1 car.

However with care a cautious driver can experiment to see if slightly larger steering input or braking starts to produce indications of instability, used intelligently it can inform on the likelihood of serious instability.

 

[ProfJohnL]

...But I have actually decided to get myself a proper Nose Weight Gauge, so I can check out my nose weight due to being 75kg..

Before you spend money on a noseload gauge, you most likely already have a method of more than adequately measuring it. You will need caravan step bathroom scales, some magazines, and a tape measure.

Load the car and caravan with the luggage and people who will travelling. Pull up on a perfectly flat surface.

Measure the height of the tow hitch from the ground. (This will of course vary depending on how the car and caravan are loaded)

Un hitch the caravan and chock the wheels and leave the handbrake off.

Using the caravan step as a base, set up a set of bathroom scales on to of the caravan step and adjust their height by putting magazines underneath the scales so the hitch will be at the same height as when it was coupled to the car.

you might want to put a bag over the hitch to prevent marks. Rest the caravans hitch on the scales make sure the jockey wheel is raised off the floor, and read the noseload measurement.

 

[otherclive]

Before you spend money on a noseload gauge, you most likely already have a method of more than adequately measuring it. You will need caravan step bathroom scales, some magazines, and a tape measure.

Load the car and caravan with the luggage and people who will travelling. Pull up on a perfectly flat surface.

Measure the height of the tow hitch from the ground. (This will of course vary depending on how the car and caravan are loaded)

Un hitch the caravan and chock the wheels and leave the handbrake off.

Using the caravan step as a base, set up a set of bathroom scales on to of the caravan step and adjust their height by putting magazines underneath the scales so the hitch will be at the same height as when it was coupled to the car.

you might want to put a bag over the hitch to prevent marks. Rest the caravans hitch on the scales make sure the jockey wheel is raised off the floor, and read the noseload measurement.

I find that doing it with the bathroom scales method allows me to then measure noseweight with my gauge more quickly. In effect the scales are used to calibrate the gauge. With loadings being pretty standard in the van I don’t get much variation so the use of the gauge allows speedier checking.

 

[Marsh Harrier]

Luckily I ave a long level drive, so can hook up the caravan up on the drive without any problems.

Apart form having to buy bathroom scales seems a bit of a fiddle around. the nose gauge I've purchased is an Milenco 2691 Calibrated Nose Weight Gauge Caravan Trailer, also invested in a cargo bar..

I've got a feeling that my hubby's face is going to be filled with horror, when I show him the gauge. will see it has another thing to complicate everything. But I'm the driver (he's never learnt to drive, and sadly if he had, he'd would have lost his licence quite a few years ago due to hypo unawareness)

I'm actually hoping that my normal way of loading my caravan has been correct and I don't end up faffing around half the morning trying to adjust how everything is loaded to achieve correct loading.

 

[JezzerB]

Just be aware that regardless of any kerbweight calcs 1500kg is the legal limit of you Mitsubishi PHEV and anything over that is illegal-it's one of those odd ones where kerbweight could maybe allow you to exceed what is legal. Your caravan therefore is fine and the outfit should be a decent match.

 

[Raywood]

Basically the heavier the car in comparison to the car the safer the outfit should be although there are other factors. The magazine and the C&CC do a tow car of the year test with a large number of cars each year and adjust the weight of the caravan towed to 85% of the kerb weight of the tow car or its legal limit if lower. I think it is a very long time since any car has proved to be a problem at that sort of weight.
The modern car and caravan do have far better suspension and road holding properties than they used to have and if you stick to the 85% guidelines you should have no problems. Personally I would not worry about 90% these days as a beginner but would be unhappy to suggest going beyond that. Having been made aware of the guidelines and the various opinions on here you do have to decide what you are prepared to use as a towing ratio.
Getting that right though is not the full story, as loading and noseweight need to be looked at as well. If you want information on this the Caravan and Motorhome sites Advice section should give you all you need.

 

[JezzerB]

Spot on imo Ray.

 

[otherclive]

With your prior experience of towing a caravan and the PHEV being quite a heavy tug, combined with its tow limit of 1500kg you should be fine. You are aware of the noseweigght limit and all I would add is try and get as near to 75kg as you can, but even there will be a margin for difference. Sometime I have had to adjust for nose weigh I use a 10litre drinking water container, and or toolbag, that we normally carry and just put it at the back of the van, as my van tends to be quite nose heavy. So not much need for shuffling load around. Some others will put water into the toilet flush etc.

But given your prior experience you will no doubt get a feel for how the new outfit tows. From reading the reviews of the PHEV it seems a good tow car, although the engine may have to be worked harder than diesel, but as towing mileage is likely to be secondary to a an owner's other motoring needs you were probably aware of that one any way.
Good touring.

 

[Lutz]

The maximum allowable towload on the VIN plate takes precedence over anything in the log book.

This is because actual values, as displayed on the VIN plate, may change quicker than any update of log book details

 

[Marsh Harrier]

The maximum allowable towload on the VIN plate takes precedence over anything in the log book.

This is because actual values, as displayed on the VIN plate, may change quicker than any update of log book details

That's what I thought, but I think I keep to what the recommendations says on the Log Book, at least that way I know I be within the legal limits for towing.

 

[Lutz]

Note, however, that the maximum allowable towload that the manufacturer sets only has product liability and warranty implications, but it is not a legal limit. Gross train weight is.

 

[Raywood]

I know that the towing limit is based on the ability of the car to restart on a 12% slope and is not therefore safety related but if you exceed this you can be prosecuted, as it is a legal limit or so I am told. If you are stopped and are over it then you may be prevented from driving further until the situation is corrected.
Advice on this seems to be contradictory when you search the web. It is probably not worth the risk.

 

[Lutz]

I know that the towing limit is based on the ability of the car to restart on a 12% slope and is not therefore safety related but if you exceed this you can be prosecuted, as it is a legal limit or so I am told. If you are stopped and are over it then you may be prevented from driving further until the situation is corrected.
Advice on this seems to be contradictory when you search the web. It is probably not worth the risk.

Any respectable car manufacturer will take safe handling and braking into account when specifying a towing limit, and not just the legal requirement relating to a number of hill starts on a 12% slope. After all, he retains full product liability for the vehicle, so he must ensure that it is safe when in service. However, in general, he will specify an ultimate towing limit without regard for the type of trailer, so it it is up to the vehicle owner to decide whether it is appropriate for a caravan.

If you reckon that it is a legal limit I would be grateful if you could reference the appropriate piece of legislation which refers to the subject, because I am unable to find anything to that effect. Obviously, if the value is exceeded excessively it would consitute a dangerous loading condition, which is illegal, but then one would most likely be exceeding the allowable maximum rear axle load of the towing vehicle, too.

 

[RogerL]

I know that the towing limit is based on the ability of the car to restart on a 12% slope and is not therefore safety related but if you exceed this you can be prosecuted, as it is a legal limit or so I am told. If you are stopped and are over it then you may be prevented from driving further until the situation is corrected.
Advice on this seems to be contradictory when you search the web. It is probably not worth the risk.

The towing limit as published can't be enforced because it's not plated - some cars have different limits for different gradients, useful in the flatlands of Holland or the mountains of the Alps.