towcar with space for 2 great danes

[JohnGriffiths]

The 30%, 80% and 100% all apply to caravans, the last two to other types of trailer.
80% is for caravans with hydraulic shock absorbers
100% is for caravans with shock absorbers and an integrated hitch or electronic stabiliser or the towing vehicle with TSP.
Without any foundation any percentage figure is totally arbitrary so neither 85% makes much sense nor is there a simple alternative. The only sensible advice is to keep the caravan as light as possible and the car as heavy as possible and, of course, always within the manufacturer's limits and leave it at that, without specifiying a percentage figure.

You suggest in an earlier post that a lot of work must have gone into deciding the German limits, If that's true should we not be pushing for the CC/other bodies and/or the government to be accepting these or similar guidelines/laws in the UK. There could be problems for people with earlier caravans without dampers though. Presumably all German vans have had dampers for a long time now.

 

[Lutz]

Although, of course, the majority over here have dampers, not all do. If they don't, they are simply restricted to towing at 80km/h maximum.
I'm not suggesting that the UK adopts the German regulations without a review. Conditions may be slightly different in the UK to warrant further studies. These could either confirm the said figures or lay down new ones. At least one would then know for sure that any percentage has a solid basis.

 

[RogerL]

You suggest in an earlier post that a lot of work must have gone into deciding the German limits, If that's true should we not be pushing for the CC/other bodies and/or the government to be accepting these or similar guidelines/laws in the UK. There could be problems for people with earlier caravans without dampers though. Presumably all German vans have had dampers for a long time now.

The problem with pushing for harmonisation of one set of regulations is that all the other regulations have to be harmonised as well - road standards, traffic density, vehicle AND TRAILER testing, driver testing, speed limits, drink-drive limits, etc - you can't simply impose one set of regulations in isolation

 

[Lutz]

The problem with pushing for harmonisation of one set of regulations is that all the other regulations have to be harmonised as well - road standards, traffic density, vehicle AND TRAILER testing, driver testing, speed limits, drink-drive limits, etc - you can't simply impose one set of regulations in isolation

All the more reason for someone to take on the task of either confirming the validity of the existing recommendation or to come up with a convincing alternative that stands up to scrutiny.
I don't see how one can expect any advice to take into account drink-drive limits or driver testing. It should be understood that any set of recommendations must assume that the driver is able to exercise necessary due care and attention. They cannot be expected to cover situations where this is not the case.

 

[ProfJohnL]

Good words John, but totally inadequate - beginners need simple clear advice - many caravanners simply don't have the mathematical and scientific ability to assess all the dynamic factors involved.

Roger, I agree it would be nice if there were a simple way of ensuring every caravanner could assess the stability characteristics of an outfit. Unfortunately it is a complex interaction of several factors, and reducing it to a single critera, is an over simplification, and as we have seen unreliable.

If someone wishes to chose 85% as their prefered towing ratio, then provided that choise is part of a considerd evaluation incluiding other factors such a load distribution for nose weights, road and vehicel condition, then that fine, but 85% is not the universal answer.

 

[RogerL]

The 30%, 80% and 100% all apply to caravans, the last two to other types of trailer.
80% is for caravans with hydraulic shock absorbers
100% is for caravans with shock absorbers and an integrated hitch or electronic stabiliser or the towing vehicle with TSP.
Without any foundation any percentage figure is totally arbitrary so neither 85% makes much sense nor is there a simple alternative. The only sensible advice is to keep the caravan as light as possible and the car as heavy as possible and, of course, always within the manufacturer's limits and leave it at that, without specifiying a percentage figure.

As this is a caravan forum let's restrict our debate to 30%, 80% and 100% in Germany compared to the UK.
Most UK caravans built until recently had no dampers, hitch or electronic stabiliser nor vehicles with TSP and so would be limited to 30% in Germany - now that's actually most caravans in use in the UK so very restrictive compared to our guidelines of 85% beginners and 100% experienced.
Although there are few UK caravans with dampers but without a stabiliser hitch, they would be limited in Germany to 80%, ie lower than in the UK.
So only the most recent UK caravans could do 100% in Germany - but that's an absolute limit - here 100% is still only a guideline for B+E licence holders who can exceed it if their car permits - not that I recommend it with a caravan.
On analysis, the German towing limits are LESS GENEROUS than in the UK - if I'm right in my recall that German caravans need testing at regular intervals, unlike the UK, then all discussion about increasing towing ratios in the UK up to German levels is totally pointless.

 

[Lutz]

I think you have misunderstood the German regulations. They do not place a blanket weight ratio limit on any outfit. If the manufacturer's spec allows, it is still perfectly legal to tow a caravan at over 100%, but then one is limited to a lower maximum speed of 80km/h instead of 100km/h. The paper that was put out by the University of Bath supports the theory that things start to get critical at speeds of around 55mph (88km/h), so this is in line with the differential speed limits for caravans in Germany.
80km/h remains the regular speed limit over here for all heavy vehicles and those towing a trailer. The 100km/h speed limit was added a few years ago as a concession to reflect technical improvements that have been introduced both on towcars and caravans in recent years. There is therefore a case for allowing higher weight ratios subject to the fulfilment of certain technical conditions. This makes a 85% recommendation for all unrealistic.

 

[RogerL]

I think you have misunderstood the German regulations. They do not place a blanket weight ratio limit on any outfit. If the manufacturer's spec allows, it is still perfectly legal to tow a caravan at over 100%, but then one is limited to a lower maximum speed of 80km/h instead of 100km/h. The paper that was put out by the University of Bath supports the theory that things start to get critical at speeds of around 55mph (88km/h), so this is in line with the differential speed limits for caravans in Germany.
80km/h remains the regular speed limit over here for all heavy vehicles and those towing a trailer. The 100km/h speed limit was added a few years ago as a concession to reflect technical improvements that have been introduced both on towcars and caravans in recent years. There is therefore a case for allowing higher weight ratios subject to the fulfilment of certain technical conditions. This makes a 85% recommendation for all unrealistic.

So the reason that some German towing limits may appear higher than the UK is where the speed limit is lower, ie 80kph (50mph) - there's been a lot of comparing "apples with pears".
The 85% guideline isn't intended to apply TO ALL - it's for beginners, which is not unrealistic, possibly too high!

 

[Lutz]

So the reason that some German towing limits may appear higher than the UK is where the speed limit is lower, ie 80kph (50mph) - there's been a lot of comparing "apples with pears".
The 85% guideline isn't intended to apply TO ALL - it's for beginners, which is not unrealistic, possibly too high!

The comparison is not between apples and pears because the technical conditions referred to apply to the 100km/h speed limit and that's basically the same as the UK 60mph one.
If the 85% is "possibly" too high, as you have said yourself, then it could just as well "possibly" be unnecessarily low. Until someone puts time and effort into establishing what is really suitable, we shall not know.
To my knowledge, the majority of sources that recommend 85% do not state that it applies to beginners only. Only when confronted by the argument that higher weight ratios are perfectly legal do they add a note to that effect.
Another issue which makes the whole concept of a fixed percentage weight ratio recommendation questionable is that weight ratio always reflects a worst case scenario that rarely, if ever occurs, i.e. the towcar in its lightest possible condition versus the caravan in its heaviest possible condition. Simply by transferring payload from caravan to car the actual weight ratio can easily be brought down to a more favourable level.
Here, an example:
Towcar, kerbweight 1400kg, GVW 1800kg
Caravan, MIRO 1200kg, MTPLM 1400kg
Weight ratio on paper = 100%
If both vehicles are fully laden (and this is probably the most likely case for a family going away on holiday) the actual weight ratio would be brought down to 78%.
In a best case scenario, (caravan empty but the car fully laden) the actual weight ratio would even drop down to 67%.
However, for comparison purposes, the weight ratio will always remain 100% and therefore well outside the 85% recommendation.

 

[ProfJohnL]

The Bath University studies have produced a limited finding that an optimal maximum speed is about 55mph, it should be noted that it related to a particular tow car - an old Mondeo estate.

We have no reports of how the same test trailers might respond to a different to car, so the there is a strong possability the limiting factor may be heavily influenced by the tow vehicle.

The tow ball on the Mondeo used has a substantial rear overhang relative to the rear wheels. Worn dampers and bushes may also affect the stability.

At this stage it might be missleading to assume that Bath's findings apply to all outfits.

 

[Lutz]

Quite true, Prof, but the very fact that, in at least one instance, the Bath University study determined a threshold speed less than the UK speed limit gives one reason to think.

 

[RogerL]

Lutz - I quote from the current copy of the NCC Towing Code:-
http://www.nationalcaravan.co.uk/images/resources/Caravan_Towing_Guide_amended.pdf

The caravan industry recommends:
For a novice caravanner, ideally, this ratio should not exceed 85%.
For an experienced caravanner the maximum recommended ratio is 100%, provided the figure is permissible
in respect of the tow car’s published capability.

There seems to be a lot of mis-information being posted and I'm surprised at you Lutz.

 

[Lutz]

I apologise if I have over-generalised, but the Camping and Caravanning Club is very conservative in their advice and only reluctantly admits that "some experienced caravanners do go over 85%" as it is not a legal requirement. However, whether the novice or the experienced is concerned, it does nothing to affect the argument that there is no verifiable evidence to support a recommendation for a 85% weight ratio and no source has stated what technical conditions must be satisfied when applying the 85% recommendation. For example, one should at least differentiate between caravans fitted with shock absorbers and those without, or pop-up caravans, as these are inherently more stable. Even the 100% recommendation needs to be qualified. If one remains below the treshold speed of the particular outfit, it would recover from instability of its own accord even if the weight ratio exceeds 100%.

 

[ProfJohnL]

Hello Roger,

Your quotes from the NCC regarding towing ratio are exactly what I object to.

There is no evidence of how much benefit there is at towing at 85% say compared to 100%. It is an unproven, and so far unsubstantiated stance that the NCC has spread around.

Good sense suggests that keeping towing ratios low should be beneficial, BUT no one has been able to quantify the benefit, and how it inter-relates with the other critical factors that affect stability.

These NCC figures over simplify what is a complex subject, and by trying to reduce towing characteristics down to one calculation based on theoretical and actually highly inaccurate figures, is misleading.

Having said that I object to the use of a fixed 85% I cannot disagree with the principal of keeping trailer masses small.

 

[manwithabeard]

Getting back to the original thread.
So it would be ok to pair a Mondeo estate 2.0ltr 163 diesil with a kerbweight of 1573kg as it has a Max Towable weight of 2000kg and my caravan is1600kg
Not really interested in debates about guidelines or continental rules. Just is it safe or am i going to end up in a ditch.

 

[Lutz]

Just is it safe or am i going to end up in a ditch.

That's a question no-one is able to answer as it all depends with how much due care and attention you drive and what technical safety features the outfit is equipped with. Anything can be safe if you treat it accordingly. Technical features, like stabilisers, etc., help in reducing the risk further.

 

[xtrailman]

Getting back to the original thread.
So it would be ok to pair a Mondeo estate 2.0ltr 163 diesil with a kerbweight of 1573kg as it has a Max Towable weight of 2000kg and my caravan is1600kg
Not really interested in debates about guidelines or continental rules. Just is it safe or am i going to end up in a ditch.

My advice is don't do it.
Nothing posted previously gives a case for towing at 100%.
If you want a rig were the car is totally in control, then tow below 85%.
From my personal experience the best tow i ever had was with my first caravan, which had the lowest ratio.
I agree other factors such as loading and nose weight, along with speed, should all be considered, so towing at a low ratio isn't a guarantee of stability, but you know it makes sense.
While i now tow at around 92%, the caravan has shockers, ATC, AKS, and balanced wheels.
I certainly wouldn't tow higher, in fact i have reduced my tow speed to 55 mph, this gives me more stability, and extra MPG.
Get a lighter caravan.

 

[JonnyG]

Silly question reallly, it is a legal match,and the ditch is full of caravans being towed by vehicles that had matches way under the so called 85% rule.
so ending up in a ditch is more to do with the driver than any weight matches........

 

[Lutz]

Exactly, JonnyG

 

[xtrailman]

Why didn't i think of that.
The chap with the overturned caravan, or in a ditch, simply couldn't drive!
Simples.

 

[forestgump]

volvo artic with fridge trailor have you a class 1.

 

[ProfJohnL]

Ray is entitled to his opinion, but his last reply I feel is very misleading.

Quote
"If you want a rig were the car is totally in control, then tow below 85%."

It is very dangerous to assume that any outfit will be in total control simply based on on a weight ratio.

JonnyG has eloquently reiterated the fact that even sub 85% outfits have instability issues.

Good towing is down to a combination of careful decisions, and weight ratio is only one of several. To be fair, Ray does acknowledge this, but his adherence to 85% is a dogmatic response and not based on a logical and scientific analysis of the issues.

There is a body of opinion that believes that towing at 100% is likely to cause control issues, It might, but there are many journeys made at 100% or more where no problems have arisen, but perhaps that is result of extra care and attention to other factors that enable the outfit to be controlled safely.

There is nothing fundamentally wrong or illegal at towing up to the tow weight limit of the car, but it does require intense care so it is sensible to keep the trailer weight as small as possible to ease all the issues.

 

[Lutz]

Why didn't i think of that.
The chap with the overturned caravan, or in a ditch, simply couldn't drive!
Simples.

I wouldn't make a statement as sweeping as that, but in the vast majority of cases the chap with the overturned caravan either had a momentary lapse of due care and attention, or he was going faster than what the conditions allowed or he reacted incorrectly to a traffic condition ahead (or a combination of all three).

 

[Jo-AnneFairway5402010]

Empty post (likely not intentional - probably an Internet Explorer issue!)

 

[joeby]

my wife owns a 4x4 Nissan Terrano which we use for over 90% of the time for towing , but some times we use my car which is a Ford Mondeo 130 TDCI Estate , the caravan is a twin axle Lunar Lexon 640 1600 kg fully loaded , it does not mean you have to load to the full amount , our kids are all adults so there is just the 2 of us , so i lower the backs seats in the Mondeo which give oodles of room , and put the awning , fishing tackle , aquarolls , wastemaster , caravan jack , food , into the rear of the car , towing about 90% ,and the only difference between the 2 vehicles is the mondeo has more excelleration going up hills , the Terrano is always in a lower gear than the Mondeo , but as we caravan all year the Terrano gets used the most , once in the Mondeo we were in the middle lane of the M4 as the inside was going to turn off to the left a car came alongside us in the outside lane and as he drew parralel with us he started to come into our lane and i had to swerve into the empty inside , and it was steady as a rock , the only snag with the mondeo is taking off from stanstill on a hill is to go easy on the pedal otherwise you will have front wheel spin , or the excellerator will lock