Loading your car to reach an 85% match

[TommoEll1980]

Hi,

I have been pondering the idea of increasing the tow car load to reach the desired 85% weight ratio match

For example:

Vauxhall insignia tourer kerb weight = 1600kg
85% match = 1360kg

Insignia max Gross weight (fully loaded with fuel passengers and luggage) = 2285kg
minus towball limit of 85kg = 2200kg
85% match = 1870kg

So as long as you don't exceed the 1600kg towing limit for the car, and as long as you put enough weight in the car, you could tow up to 1600kg and still meet the 85% recommended towing match.

Is this right or have i got this completely wrong?

Any information is good information

Cheers
Tom

 

[ProfJohnL]

Hi,

I have been pondering the idea of increasing the tow car load to reach the desired 85% weight ratio match

For example:

Vauxhall insignia tourer kerb weight = 1600kg
85% match = 1360kg

Insignia max Gross weight (fully loaded with fuel passengers and luggage) = 2285kg
minus towball limit of 85kg = 2200kg
85% match = 1870kg

So as long as you don't exceed the 1600kg towing limit for the car, and as long as you put enough weight in the car, you could tow up to 1600kg and still meet the 85% recommended towing match.

Is this right or have i got this completely wrong?

Any information is good information

Cheers
Tom

Hello Tom

Strictly speaking you have not got the principle of the 85% correct, so your suggestion does not meet the 85% guidance. Please note I have used the word guidance, as that is all the 85% is, but it's not without some merit, so its shouldn't be summarily ignored.

The 85% guidance is ALWAYS on the the tow vehicles lowest possible weight i.e. its Kerb Weight, and the the trailers Maximum Authorised Mass (MAM) otherwise known as the Maximum Technical Permitted Laden Mass or MTPLM. So changing how you load a tow vehicle or trailer does not change the calculation.

I personally do challenge the efficacy of this method, but there is no other simple way of producing a comparator without going into much greater detail and complexity. But I do emphasise that adhering to the guidance offers no guarantees of safety or legality.

Legally and in theory you could tow caravan that does not exceed the tow vehicles stated maximum towed load, But that also does not infer the outfit would be safe. and in particular trying to tow a caravan whose weight was at the tow vehicles weight limit is not wise. This is because the tow vehicles type approval process determines the vehicles towed weight limit through a set of prescribed test that use and ideal trailer, and caravans are not ideal.

Compared to an ideal trailer, caravans are very much larger, and are affected by windage and other aerodynamic and dynamic forces that a small trailer would not. The large size of a caravan means that side winds and bow waves from other vehicles will produce significantly larger forces that will disturb the tow vehicle much more. The UK industry have acknowledged this and produced the 85% and 100% guidance

Whilst I have not specifically stated it yet , You must never exceed the towed weight limits of the tow vehicle.

Even though a tow vehicle may have a lofty towed weight limit, towing a caravan that matches that limit may be legal from the weight perspective, but if it causes the outfit to become unstable it could be classed as unsafe and that could lead to prosecution for an unsafe load.

Weights do have a part play in producing a good towing experience, they are far from the only factors, and I would argue they are not the single most important. You need to also consider

Load distribution
Nose load
Vehicle condition
Tyre condition and pressures
Suspension and other general condition
and probably the most significant factor is Driver habits and skills.

 

[colin-yorkshire]

have i got this completely wrong?
Cheers
Tom

in one word Yes.
in more than one word Yes. Yes.
there are many factors to consider the Prof has outlined some of them.
but basically you cannot increase the weight of the tow car just so you can tow a heavier trailer. or decrease the overall tow ratio of a too heavy trailer by juggling the overall maximum weights.
the parameters you have to work with are the the maximum weights of.
the front axle
the rear axle
the total weight of the tow car
the total tow weight of the trailer
the nose weight
the weight of the combined unit.
how you load the outfit is up to you providing none of the above maximums are exceeded.

 

[Raywood]

I am afraid you do have the wrong idea on this as the other have said. The ratio assumes some load in the car although this would not be the MGW.
The Insignia is a decent tow car, but its towing ability performance wise also depends on the engine fitted, and I assume with a maximum towing limit of 1600 kg it might be a smaller one. You do have to take this into account as towing at the limit usually means the engine can struggle on hills and acceleration poor with heavy fuel consumption. The limit is usually based on the strength of the drive line, and is what the car should be able to restart five times on a 12% hill, and has nothing to do with towing in the real world.
Personally if you are new to towing I would try to stick fairly close to 85% of the kerb weight but exceeding this by a modest amount should not be a problem but probably no more than 90% in my view.

 

[Woodentop]

Look for the ratings plate on the car - usually low down on the nearside B-pillar (the pillar between front and back doors.) The top two figures show the gross train weight (the larger number) and the maximum weight of the car (the lower figure.) Subtracting the latter from the former will give you the maximum weight you can tow. The figure against 1 is the maximum front axle capacity and that against 2 is the maximum rear axle capacity.

One other point: since we seem to be talking large figures when did you pass your driving test? If on or after 1/1/97 you will need a B+E licence to tow a train weight in excess of 3500Kg - and this is plated weights not actual if the actual weight is lower. Before that date you get it automatically through so-called grandparent rights.

Final point: with your caravan connected and the side lights on, open the tailgate (I assume tourer means estate) and make sure the caravan tail lights stay on. A former colleague of mine who had an Insignia estate as a co. car asked for it to be supplied with a towbar fitted. It seems the installer did not use the Vauxhall electronics pack and just cut into the tailgate sidelights, not realising that when the tailgate is lifted the lights on the tailgate go off to be replaced by those on the body inside the tailgate.

 

[gspice1980]

I realise this thread is a few weeks old, however I have direct experience towing with an Insignia Sports Tourer 130 bhp at >85% match, my caravan has a MAM of 1530 kg.

I have towed using this combination for about a year, and it is ok, but not great. The outfit is very sensitive to weight distribution in the caravan and I took to keeping all clothes and loose items on the floow near the axle and a few things forward of the axle low down to keep the nose weight at ~80kg. I had a few worrying sways on the motorway when passing/being passed by high sided vehicles, so kept it at or at or below 55 mph.

I have now changed to a VW Amarok, which is a different towing beast altogether. Of course changing cars is not often an option, as others have pointed out, if you are towing at near the limit of the car than extra care must be taken when loading the van/car and also when driving.

 

[Raywood]

I realise this thread is a few weeks old, however I have direct experience towing with an Insignia Sports Tourer 130 bhp at >85% match, my caravan has a MAM of 1530 kg.

I have towed using this combination for about a year, and it is ok, but not great. The outfit is very sensitive to weight distribution in the caravan and I took to keeping all clothes and loose items on the floow near the axle and a few things forward of the axle low down to keep the nose weight at ~80kg. I had a few worrying sways on the motorway when passing/being passed by high sided vehicles, so kept it at or at or below 55 mph.

I have now changed to a VW Amarok, which is a different towing beast altogether. Of course changing cars is not often an option, as others have pointed out, if you are towing at near the limit of the car than extra care must be taken when loading the van/car and also when driving.

The Insignia is generally regarded as a good tow car but you were using one of the lower powered models and it may be it had a lesser suspension, I do not know. Certainly it should have been well able to handle the caravan but I do wonder if you got one of those combinations that on paper look good but for no apparent reason seem to be a problem.
The Amarok is a very different beast and far heavier and should hardly notice the caravan, but I would check the guarantee on the caravan if it has one as that might exclude the use of this as a tow car.