Kerbweight

I had a dozen happy years towing a small Eriba all over Europe with a Freelander- the caravan was exactly half the weight of the car. That ratio works a treat - especially with a 2.2 litre engine under the car lid. 

 

As I said, one has to drive to suit the conditions. This may mean that to tow a 2.5m high empty box trailer safely you would have have to reduce your speed to 40mph whereas the low loader can be towed safely at over 60mph, but if that is taken into account, one is as safe as the other.

superstition? I think that is really not the appropriate word here. 

The thing is you use whatever towing rule/guidance/percentage you want. Within the law no one, NCC, club... is forcing you to use any figure in your towing. Do what you think best. 

The whole conversation is highly unscientific and that is the problem with this 85% guidance, it also lacks any scientific basis.  For example, if you look in the ALKO caravan chassis brochure, there is a section on the weight reduction you can legally get from a stabiliser device like the AKS.  ALKO calculates that having a chassis with an AKS stabiliser allows you to tow an additional 20% of weight from the same tow vehicle.  The example they give is a tow car weighing 1,600kg can tow a caravan maximum laden 1,600kg with a stabiliser but only 1,280 without, i.e. the stabiliser allows an additional 320kg.  ALKO know a thing or two about trailers.  None of this information is taken into account in the 85% rule.  Its a dinosaur. See page 44-45

https://www.alko-tech.com/sites/default/files/uploaded_files/EN/499668_htk-caravan_12-2018_en.pdf

The user and all related content has been Deleted User

The trailertenter with no name seems determined to operate on the "what can I get away with" rather than approaching from" what is safe". We are a year into Covid with numerous restrictions and lockdowns because people have taken a similar stance regarding prudent rules. When you are on the road just stay away from me!

I think that you have completely misunderstood AlKo's publication, which is, admittedly, misleading. The regulation referred to in their publication applies only to Germany and fitment of a stabiliser is only to one of several requirements that must be fulfilled in order to allow towing at 100km/h instead of the regular 80km/h speed limit that applies in that country. A towing vehicle fitted with an electronic Trailer Stability Assist feature is equally acceptable as an alternative to an AKS unit.

If one is prepared not to exceed 80km/h there is no weight ratio restriction.

It does not, in any way, allow higher towloads than what the manufacturer of the towing vehicle specifies. It certainly does not allow you to tow an additional 20% of weight with the same towing vehicle, as you suggest.

Note that an 85% weight ratio recommendation is unheard of on the Continent. Other than in Germany one is limited only by the vehicle manufacturers' specifications.

In my view Trailertenter, you are hopelessly over complicating this by mixing what is legal with the 85/100% ‘guidelines’, single/twin axle, ATC etc etc. I do agree with you the 85/100% guidelines are out of date insofar as not reflecting safety improvements, AND they are too often mis-understood as having a legal standing. I would add that sur le continent there are no such guidelines (as Lutz also refers). The starting point is simple legality, is the car/towed unit (caravan) combination legal and that is straightforward to establish. Second, is the driver qualified to drive it (B + E license). Following that is checking your insurance (some insurers limit the cover to 100% max ratio) and are you, the driver, confident with the resulting set up? The issue of whether ATC adds 5% is eroneous and i defy anyone to tell me they can tell the difference that 5% makes when towing, that 5% could simply be the difference between the car having a full/empty fuel tank. I have towed both single and t/a and there are benefits of both however i am not aware of any accident data to indicate one is safer than the other. There is no gaurantee of safe anything in life including towing. Many who tow are firmly in the camp that regard 86% as reckless and get the smelling salts out when anyone suggests towing over 85%. Others make their own minds up (me). The old adage used to be buy the biggest heaviest most powerful car you can afford to tow the smallest lightest caravan you can manage.

 

My point is that surely the NCC guidance should be scientifically assessed and updated for the advances in vehicle and trailer technology.  It should not remain unchanged for 30 years.  If I have a new twin axle trailer with a modern stabiliser and ATC system then it is absolutely not the same as pulling a 20 year old single axle with no stablisier or ATC, but the NCC guidance takes none of this into account.  Of course I realise the ALKO data are not UK law but the point is they express the benefit of having a stabiliser in terms of additional load that can be towed, i.e. they put it into numbers.  How is there no such attempt to do this by the NCC? They should test these devices and make the calculations, as buyers we need to know are these products actually delivering the extra stability they promise.  It seems the whole world is moving in the opposite direction to the caravan industry approach of 'bigger car is always better'.  Rather, the NCC should be doing scientific tests of what is the SMALLEST car that can safely tow to reduce the environmental impact of the industry. 

NCC is merely a Trade Body. They are there to run a profitable business representing the interests of members and we, the retail buying public are not members of NCC. The 85% thing goes back donkey's years and has never had any scientific basis. We should all forget it as no more than an old wives tale.