We are thinking of up grading the car to a New Ford Grand C-Max 2.0 TDCI Auto will it pull this Lunar Ultima 544 Caravan
- Thread starter Beachball
- Start date
- Jul 30, 2007
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Hi Beachball.
I believe the 85% recommended towing weight of the C Max is 1389kg.(Not sure what the maximum noseweight is).
The Ultima 544 maximum laden weight is 1376kg.
Im sure someone will give you more information.
Adrian
I believe the 85% recommended towing weight of the C Max is 1389kg.(Not sure what the maximum noseweight is).
The Ultima 544 maximum laden weight is 1376kg.
Im sure someone will give you more information.
Adrian
- Mar 14, 2005
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Hello Mark,
Caravans and other trailers do not have a fixed nose weight. As soon as you add any item to the caravan in front or behind the axle, the nose weight will change.
You adjust the nose weight by distributing the items around the caravan. Items positioned in front of the main axle will increase the nose weight , and items loaded behind the axle will reduce the nose weight.
The nose weight to aim for must be a minimum of 4% of the MTPLM of the caravan, and no less than the towball maximum permitted by the car manufacture (see the data plate on the cars towball) and less than the maximum permitted by the trailer manufacture. The Caravan Club suggest aiming for 5 to 7% of MTPLM.
You should adjust the nose weight so the outfit tows comfortably and safely, generally this means aiming to wards the top of the available limits.
Caravans and other trailers do not have a fixed nose weight. As soon as you add any item to the caravan in front or behind the axle, the nose weight will change.
You adjust the nose weight by distributing the items around the caravan. Items positioned in front of the main axle will increase the nose weight , and items loaded behind the axle will reduce the nose weight.
The nose weight to aim for must be a minimum of 4% of the MTPLM of the caravan, and no less than the towball maximum permitted by the car manufacture (see the data plate on the cars towball) and less than the maximum permitted by the trailer manufacture. The Caravan Club suggest aiming for 5 to 7% of MTPLM.
You should adjust the nose weight so the outfit tows comfortably and safely, generally this means aiming to wards the top of the available limits.
- Jul 15, 2008
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- Mar 14, 2005
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Thank you Gaffer,
Unfortunately I cant edit the post but here is the correction:-
The nose weight to aim for must be a minimum of 4% of the MTPLM of the caravan, and LESS THAN the towball maximum permitted by the car manufacture (see the data plate on the cars towball) and less than the maximum permitted by the trailer manufacture. The Caravan Club suggest aiming for 5 to 7% of MTPLM.
Unfortunately I cant edit the post but here is the correction:-
The nose weight to aim for must be a minimum of 4% of the MTPLM of the caravan, and LESS THAN the towball maximum permitted by the car manufacture (see the data plate on the cars towball) and less than the maximum permitted by the trailer manufacture. The Caravan Club suggest aiming for 5 to 7% of MTPLM.
Prof John L said:
Sorry Prof.
Just edited your post.
CC state actual laden weight, not MTPLM.
This could make a difference.
Mat
By answering these questions, you may get a better idea.
As you wont know the actual laden weight of the caravan take the average of the MIRO and MTPLM.
1) % the MTPLM is of the tow cars max permissable tow weight it should be <101%
2) % the MTPLM is of the tow cars kerb weight it should be <86%
3) % the max permissable nose weight is ( lowest value of car and caravan hitch/ chasis given values) of the caravans actual loaded weight it should be 4 to 7%
4) BHP per tonne of the actual outfits train weight best if >40
If all the values are ok then it is a good starting point.
Mat
As you wont know the actual laden weight of the caravan take the average of the MIRO and MTPLM.
1) % the MTPLM is of the tow cars max permissable tow weight it should be <101%
2) % the MTPLM is of the tow cars kerb weight it should be <86%
3) % the max permissable nose weight is ( lowest value of car and caravan hitch/ chasis given values) of the caravans actual loaded weight it should be 4 to 7%
4) BHP per tonne of the actual outfits train weight best if >40
If all the values are ok then it is a good starting point.
Mat
- Mar 14, 2005
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Hello Mat,
First of all the CC do not write the rules, they can only offer guidance.
Now whilst the the CC may suggest using actual ldaden weight, how many people actually know their actual laden weight. Inpractice very few unless thay have just used weigh bridge. Consequently using the MTPLM is a very safe way of ensuring you remain within the regulations under all conditions without having to resort to weigh bridges.
Your method of calulating at 1) is technically wrong, as 100.1% is still less than your suggested figure of 101% but they are both over the leagal value. you shouldl use <=100% A small but legal point.
The same argument applies to 2) but for various well discussed reasons, the CC's suggestion of 85% has absolutely no legal relevance. though the concept of keeping the trailers weight a small as possible is good advice, but 85% offers absolutely no guarantee of safety or satisfactory towing performance.
There is a legal significance to 4% but again the CC.s suggestions is only guidance and extensive towing experience suggests that the nose weight is usually best if close the maximum values permitted by the outfit. Technically the minimum value must not be less tha 25Kg, which is largely irrelevant for caravans.
I do agree with the 40BHP /tonne but modern diesels can often be quite aqdequat with lower figures.
First of all the CC do not write the rules, they can only offer guidance.
Now whilst the the CC may suggest using actual ldaden weight, how many people actually know their actual laden weight. Inpractice very few unless thay have just used weigh bridge. Consequently using the MTPLM is a very safe way of ensuring you remain within the regulations under all conditions without having to resort to weigh bridges.
Your method of calulating at 1) is technically wrong, as 100.1% is still less than your suggested figure of 101% but they are both over the leagal value. you shouldl use <=100% A small but legal point.
The same argument applies to 2) but for various well discussed reasons, the CC's suggestion of 85% has absolutely no legal relevance. though the concept of keeping the trailers weight a small as possible is good advice, but 85% offers absolutely no guarantee of safety or satisfactory towing performance.
There is a legal significance to 4% but again the CC.s suggestions is only guidance and extensive towing experience suggests that the nose weight is usually best if close the maximum values permitted by the outfit. Technically the minimum value must not be less tha 25Kg, which is largely irrelevant for caravans.
I do agree with the 40BHP /tonne but modern diesels can often be quite aqdequat with lower figures.
Prof John L said:
Yes you are quite correct, the CC only offer advice, but even that has good practice behind it, as the 85% guide line lends itself to prove.
My point is that the difference between ACTUAL, MIRO and MTPLM, as well you know will be 100+ kg, sizable difference when calculations are concerned, hence why i said to use the average of the two, to give a reasonable value....
I also agree that acting on the side of caution is good practice, hence MTPLM would be better used, in the absence of true figures.
The issue of being "technically" incorrect, i do find a little bit finiky Prof, when you are talking decimals of percentage points !!!
In any respect lets not detract from the OP's question, to which we have both contributed to in good faith.
Mat
- Mar 14, 2005
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I defence of the Prof's reply, I think one should refrain from talking about any decimal percentage points. Anything over 100% would be illegal for those who have a Category B licence issued after January 1997, and no decimal points allowed. 100% is the absolute maximum.mat said:
I think that was the jist of what the Prof was trying to get at, too.
ps: The regulations say that the noseweight shall be "no less than 4% of the maximum permissible towable mass and not less than 25kg". In other words, it's not the actual weight that counts, but the MTPLM.
- Mar 14, 2005
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Hello Mat
Thank you for your reply, AS you may well have noticed I do tend work to the facts and not traditions.
Lutz has expressed my point in an alternative manner regards limits. Where legal limits are involved the margin for adjustment is defined by the limits.
Despite extensive discussion on this and other forums, the basis of the caravans industries 85% guideline has never been published.
The assumption that 85% is a good safety margin has never been proven, and it is likely that of all incidents involving the stability of an outfit a majority will actually have been no greater than 85% loaded. Thus there is reasonable cause to doubt the choice of 85% as a guide figure to be used in the context of suggesting safe towing.
Until the source information that allowed the 'panel' to pronounce '85% is good' is published, explained and verified then the choice of a rigid 85% as being the industries prime method of predicting a good towing match should be discontinued in favour of advocating the smallest trailer weight as possible, until a more accurate proven method can be devised and introduced.
Thank you for your reply, AS you may well have noticed I do tend work to the facts and not traditions.
Lutz has expressed my point in an alternative manner regards limits. Where legal limits are involved the margin for adjustment is defined by the limits.
Despite extensive discussion on this and other forums, the basis of the caravans industries 85% guideline has never been published.
The assumption that 85% is a good safety margin has never been proven, and it is likely that of all incidents involving the stability of an outfit a majority will actually have been no greater than 85% loaded. Thus there is reasonable cause to doubt the choice of 85% as a guide figure to be used in the context of suggesting safe towing.
Until the source information that allowed the 'panel' to pronounce '85% is good' is published, explained and verified then the choice of a rigid 85% as being the industries prime method of predicting a good towing match should be discontinued in favour of advocating the smallest trailer weight as possible, until a more accurate proven method can be devised and introduced.
Parksy
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- Nov 12, 2009
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One would imagine that the advice given by both clubs suggesting 85% as a safe weight percentage to use as a figure for those inexperienced in towing to aim for when choosing a caravan would be based on the collective experience of these clubs John.Prof John L said:
The ratio of 85% that is normally recommended for inexperienced towing vehicle drivers in respect of caravans could well be based on factors other than weight and legal limits alone and a vehicle manufacturers weight limit is an indication of the towing ability of that vehicle and not of it's stability.
Neither club have ever set out to prove that the 85% figure offered as advice is any guarantee of safety as far as I know. Although a different weight ratio between towing vehicle and caravan may well be just as safe and perfectly legal surely their figure of 85% allows sufficient margin to ensure that there would be little chance of illegal weight ratio being used inadvertently by novice caravanners and road.
Weather and driving conditions and driver experience ( or lack of it) may also play a part in the clubs recommendation of 85%.
The assumption that 85% is a good margin has never been published I'd agree but 85% is not proven to be a bad margin either.
This constant contradictory and possibly confusing 'advice', and the protracted arguments between forum members which often follow and which add to the confusion, is more dangerous to newcomers to caravanning who use this forum to ask for simple advice than the guidance given by both clubs and many other caravan organisations, no matter what basis is used by the experts who decided on an 85% figure.
- Mar 14, 2005
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Hello Parksy,
I am not about to reiterate all the arguments for challenging 85% as a recommendation for towing ratio - I am sure you have read all of them.
I will restate however that it is inconceivable that a single fixed ratio will endow all outfits with a defined level of control.
It is also a major flaw with the industries contention that weight ratio should be given such prominence over all the other factors that contribute to the towing safety and experience.
It is a continual regret that the organisations that suggest this single figure approach will not stand up and explain and justify the adoption the recomendation or wont add other factors to consider to the guidance. I think it is difficult assume the people that produced the 85% figure are experts in caravan towing.
I am not about to reiterate all the arguments for challenging 85% as a recommendation for towing ratio - I am sure you have read all of them.
I will restate however that it is inconceivable that a single fixed ratio will endow all outfits with a defined level of control.
It is also a major flaw with the industries contention that weight ratio should be given such prominence over all the other factors that contribute to the towing safety and experience.
It is a continual regret that the organisations that suggest this single figure approach will not stand up and explain and justify the adoption the recomendation or wont add other factors to consider to the guidance. I think it is difficult assume the people that produced the 85% figure are experts in caravan towing.
Parksy
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- Nov 12, 2009
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The 85% weight recommendation doesn't attempt to claim to endow all outfits with a defined level of control John, it is merely a recommendation from both clubs and other caravan organisations for a caravan and tow vehicle weight ratio suitable for those who are not experienced in towing and was possibly intended to prevent new caravanners from choosing caravans that are too heavy to be towed legally and safely.
As far as I'm aware the caravan industry does not give undue prominence to this weight ratio over other safety and weight factors which could affect safety and stability when towing.
I'll concede that some forum members mistakenly refer to the '85% rule' but this may be because the figure of 85% is an easier fact to remember than, say, noseweight as a percentage of the laden weight of a caravan.
This is hardly the fault of the organisations who recommend the 85% figure to inexperienced towing vehicle drivers.
I know for a fact that the C&CC of which I'm a member does indeed add many other relevant factors to the guidance for new caravanners, after all let's not forget that it is new and inexperienced caravanners for whom this advice is intended.
I suspect that the CC also add similar other factors to the 85% recommendation, caravan forums in general add masses of related information to help new caravanners and those inexperienced in towing so when taken into context I'm not sure why you believe that the figure is given undue prominence, it is a starting point and that is all but it's a safe starting point.
The 85% figure needs no justification, it is a safe figure purely from a weight standpoint and a margin is allowed to take into account the inexperience of the towing vehicle driver, the road conditions and the weather conditions likely to be encountered.
No one could reasonably argue that the 85% recommendation is unsafe when the supplementary information provided by clubs and towing organisations is also adhered to but the argument that the 85% guideline is safe when all relevant factors are considered stands up to scrutiny.
I can't imagine that large organisations like the Caravan Club and the Camping & Caravanning club would risk publishing advice to their members, and to the general public who may be considering caravan ownersip, that was unsafe or unfounded.
Is your contention that these organisations have not consulted experts before issuing such advice?
Don't tell me that you're trying to imply that the CC and the C&CC wouldn't have access to 'experts in towing' and that they just make this stuff up as they go along!
As far as I'm aware the caravan industry does not give undue prominence to this weight ratio over other safety and weight factors which could affect safety and stability when towing.
I'll concede that some forum members mistakenly refer to the '85% rule' but this may be because the figure of 85% is an easier fact to remember than, say, noseweight as a percentage of the laden weight of a caravan.
This is hardly the fault of the organisations who recommend the 85% figure to inexperienced towing vehicle drivers.
I know for a fact that the C&CC of which I'm a member does indeed add many other relevant factors to the guidance for new caravanners, after all let's not forget that it is new and inexperienced caravanners for whom this advice is intended.
I suspect that the CC also add similar other factors to the 85% recommendation, caravan forums in general add masses of related information to help new caravanners and those inexperienced in towing so when taken into context I'm not sure why you believe that the figure is given undue prominence, it is a starting point and that is all but it's a safe starting point.
The 85% figure needs no justification, it is a safe figure purely from a weight standpoint and a margin is allowed to take into account the inexperience of the towing vehicle driver, the road conditions and the weather conditions likely to be encountered.
No one could reasonably argue that the 85% recommendation is unsafe when the supplementary information provided by clubs and towing organisations is also adhered to but the argument that the 85% guideline is safe when all relevant factors are considered stands up to scrutiny.
I can't imagine that large organisations like the Caravan Club and the Camping & Caravanning club would risk publishing advice to their members, and to the general public who may be considering caravan ownersip, that was unsafe or unfounded.
Is your contention that these organisations have not consulted experts before issuing such advice?
Don't tell me that you're trying to imply that the CC and the C&CC wouldn't have access to 'experts in towing' and that they just make this stuff up as they go along!
- Jun 20, 2005
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Are you ok Parksy
That was an excellent balanced well laid outpiece of advice
Interestingly enough the PC Mag technical advice area still refers to" the 85% rule".
Imo being legal is one thing but being sure you have a safety margin is another. I've towed at 100% many a time but still prefer not to go over 85% . There is no question of doubt the suction effect of a big overtaking coach feels far greater at 100% than at 85% or lower. Well that's my view. For a newbie , invariably with their wife and youngsters on board, why not be prudent rather than macho even though macho may be legal.
Of course as we all know loading , as John says still plays a crucial part but we have to start somewhere like 85% weight ratios.
That was an excellent balanced well laid outpiece of advice
Interestingly enough the PC Mag technical advice area still refers to" the 85% rule".
Imo being legal is one thing but being sure you have a safety margin is another. I've towed at 100% many a time but still prefer not to go over 85% . There is no question of doubt the suction effect of a big overtaking coach feels far greater at 100% than at 85% or lower. Well that's my view. For a newbie , invariably with their wife and youngsters on board, why not be prudent rather than macho even though macho may be legal.
Of course as we all know loading , as John says still plays a crucial part but we have to start somewhere like 85% weight ratios.
- Mar 14, 2005
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Perhaps it would put the minds of both supporters and opponents of the 85% recommendation at rest if the sources that continue to refer to it made it quite clear that the figure is arbitrary. Without such a note a novice could be lead to believe that 86% is a certain recipe for disaster.
- Mar 14, 2005
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Hello Parksey
I sense you are angling to ask me to tone down my answers and criticism of the industry recommendation of 85% on the basis that it may be making matter too confusing for readers.
The criticisms I have are I believe are well founded.
Firstly you only have to look at the number of questions raised here on PC forum and others and in the press concerning outfit matching. By far and away the single biggest factor quoted is the weight ratio. So even though the clubs may also highlight other factors, they continue to major on the weight ratio and thus perhaps unintentionally over emphasis its importance, and the public reflect that precedence.
Secondly, the press do little if nothing to change that perception, which is why so many people now refer to 85% as rule, rather than as a guideline. Even though this may be generalised colloquialism it further reinforces the notion that the value has some significance above it station, especially to people who are new to towing who read about the 'rule' in magazines and other sources of information this adds a new cycle to the reinforcement of the misconception.
You your self have just posted:
“I'll concede that some forum members mistakenly refer to the '85% rule' but this may be because the figure of 85% is an easier fact to remember.”
Sorry Parksy but what's factual about 85% in this context?
“The 85% figure needs no justification, it is a safe figure purely from a weight standpoint”
Sorry again Parksy, but the figure does need justification, because it is used in the context of suggesting a safety margin.
“but the argument that the 85% guideline is safe when all relevant factors are considered stands up to scrutiny.”
The whole basis of our concern is that it does not stand up to scrutiny.
Your post again reinforces the misconception the 85% is a safety value. There will have ave been here will be many incidence where a driver has lost control(Stability) with a ratio of 85% or less – Equally there will many cases where ratio's have been in excess of 85% and yet no untoward incidents have arisen, so there is no clear justification for the choice of 85% or any fixed figure.
From an engineering review of the issues, there are far more factors affecting stability and safety than just weight ratio. It would be extremely fortunate if all the factors could be condensed down to a single figure that confers an adequate level of safety, but it simply isn't the case, so no scientist or engineer would even suggest a single figure, they would suggest a range, or place several complimentary criteria that needed to be achieved.
I sense you are angling to ask me to tone down my answers and criticism of the industry recommendation of 85% on the basis that it may be making matter too confusing for readers.
The criticisms I have are I believe are well founded.
Firstly you only have to look at the number of questions raised here on PC forum and others and in the press concerning outfit matching. By far and away the single biggest factor quoted is the weight ratio. So even though the clubs may also highlight other factors, they continue to major on the weight ratio and thus perhaps unintentionally over emphasis its importance, and the public reflect that precedence.
Secondly, the press do little if nothing to change that perception, which is why so many people now refer to 85% as rule, rather than as a guideline. Even though this may be generalised colloquialism it further reinforces the notion that the value has some significance above it station, especially to people who are new to towing who read about the 'rule' in magazines and other sources of information this adds a new cycle to the reinforcement of the misconception.
You your self have just posted:
“I'll concede that some forum members mistakenly refer to the '85% rule' but this may be because the figure of 85% is an easier fact to remember.”
Sorry Parksy but what's factual about 85% in this context?
“The 85% figure needs no justification, it is a safe figure purely from a weight standpoint”
Sorry again Parksy, but the figure does need justification, because it is used in the context of suggesting a safety margin.
“but the argument that the 85% guideline is safe when all relevant factors are considered stands up to scrutiny.”
The whole basis of our concern is that it does not stand up to scrutiny.
Your post again reinforces the misconception the 85% is a safety value. There will have ave been here will be many incidence where a driver has lost control(Stability) with a ratio of 85% or less – Equally there will many cases where ratio's have been in excess of 85% and yet no untoward incidents have arisen, so there is no clear justification for the choice of 85% or any fixed figure.
From an engineering review of the issues, there are far more factors affecting stability and safety than just weight ratio. It would be extremely fortunate if all the factors could be condensed down to a single figure that confers an adequate level of safety, but it simply isn't the case, so no scientist or engineer would even suggest a single figure, they would suggest a range, or place several complimentary criteria that needed to be achieved.
- Mar 14, 2005
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Unfortunately, page 10 doesn't give an answer to the Prof's misgivings about the 85% recommendation.
What is more misleading is the statement "...... empty or kerb weight of the car. If you can’t find this figure in the vehicle handbook, ask your car or caravan dealer to look it up or phone The Caravan Club’s Technical Advice and Information Department, giving the make, model and year of your car."
Neither the handbook nor the car or caravan dealer nor The Caravan Club’s Technical Advice and Information Department will have anything better than a rough approximation of the kerbweight as kerbweight is specific to each and every car and variances of up to 150kg from any published data must be expected. It would be appropriate if the Caravan Club pointed this out. The only legally binding figure is that shown in the V5c certificate, where shown. However, it appears from other previous posts in this forum that quite a number of V5c's don't show the "Mass in Service".
What is more misleading is the statement "...... empty or kerb weight of the car. If you can’t find this figure in the vehicle handbook, ask your car or caravan dealer to look it up or phone The Caravan Club’s Technical Advice and Information Department, giving the make, model and year of your car."
Neither the handbook nor the car or caravan dealer nor The Caravan Club’s Technical Advice and Information Department will have anything better than a rough approximation of the kerbweight as kerbweight is specific to each and every car and variances of up to 150kg from any published data must be expected. It would be appropriate if the Caravan Club pointed this out. The only legally binding figure is that shown in the V5c certificate, where shown. However, it appears from other previous posts in this forum that quite a number of V5c's don't show the "Mass in Service".
Parksy
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Do you have access to data from police, motoring organisations and insurers which outline the findings of investigators who look into the causes of incidents which have resulted in a departure that has caused either the partial or total loss of a caravan, a towing vehicle or both, John?
I don't personally, and I have no method of proving that both or either clubs have access to such data but I'd suggest that as leading caravan insurers both clubs would be more likely to have access to this kind of information than either you or I.
I'm happy to be proven wrong on this point though.
It's a fact that both clubs and some other related organisations recommend the 85% figure, (this is what I find factual in answer to your first point) and those who pass on the advice via this and other caravan related forums remember it which is why it is referred to so often.
Salient passages from the CC information sheet kindly linked to by Sprocket read thus:
As a newcomer to caravanning, you would be
wise to stick to the generally recommended
guideline of towing a caravan weighing no more
than 85% of the empty or kerb weight of the
car. If you can’t find this figure in the vehicle
handbook, ask your car or caravan dealer to look
it up or phone The Caravan Club’s Technical
Advice and Information Department, giving the
make, model and year of your car. The Club
bases all of its testing on this guidance, which
almost invariably results in an outfit that is safe
and comfortable to tow.
Over the years The Caravan Club has tested a
vast number of cars for towing, and has quizzed
its members on many more. Therefore its
Technical Advice and Information Department
will have the ability to advise if the car you wish
to tow with is good at the job, and what size of
caravan it would best suit.
I daresay that I could find similar statements from the C&CC.
I find it incredible that the CC would print the above statements without proof of their testing and the results of such testing being available to those authorised to inspect it.
That is enough justification for me and it's adequate for any scrutiny that I and most other casual enquirers are likely to require as a basis for a starting point.
We both agree that of course there are far more factors affecting stability and safety than weight ratio but weight ratio continues to play some part in some incidents.
The 85% recommendation simply provides the basis to help a newcomer to towing to avoid an elementary error at the very outset when choosing a suitable caravan which can be towed by any given vehicle legally, safely and comfortably.
This advice is supplemented by a complementary range of separate criteria which does need to be achieved to provide a satisfactory outcome.
I do indeed feel that at times the argument and counter argument about the validity of the 85% recommendation may confuse newcomers seeking advice but I'm not attempting to censor your challenges John or to 'tone you down'.
I'm merely attempting to show that the 85% recommendation is not the only factor to be taken into consideration by those seeking advice, no organisation has tried to claim otherwise, but your challenges appear to be based on the assumption that those forwarding the 85% recommendation believe it to be so.
I don't personally, and I have no method of proving that both or either clubs have access to such data but I'd suggest that as leading caravan insurers both clubs would be more likely to have access to this kind of information than either you or I.
I'm happy to be proven wrong on this point though.
It's a fact that both clubs and some other related organisations recommend the 85% figure, (this is what I find factual in answer to your first point) and those who pass on the advice via this and other caravan related forums remember it which is why it is referred to so often.
Salient passages from the CC information sheet kindly linked to by Sprocket read thus:
As a newcomer to caravanning, you would be
wise to stick to the generally recommended
guideline of towing a caravan weighing no more
than 85% of the empty or kerb weight of the
car. If you can’t find this figure in the vehicle
handbook, ask your car or caravan dealer to look
it up or phone The Caravan Club’s Technical
Advice and Information Department, giving the
make, model and year of your car. The Club
bases all of its testing on this guidance, which
almost invariably results in an outfit that is safe
and comfortable to tow.
Over the years The Caravan Club has tested a
vast number of cars for towing, and has quizzed
its members on many more. Therefore its
Technical Advice and Information Department
will have the ability to advise if the car you wish
to tow with is good at the job, and what size of
caravan it would best suit.
I daresay that I could find similar statements from the C&CC.
I find it incredible that the CC would print the above statements without proof of their testing and the results of such testing being available to those authorised to inspect it.
That is enough justification for me and it's adequate for any scrutiny that I and most other casual enquirers are likely to require as a basis for a starting point.
We both agree that of course there are far more factors affecting stability and safety than weight ratio but weight ratio continues to play some part in some incidents.
The 85% recommendation simply provides the basis to help a newcomer to towing to avoid an elementary error at the very outset when choosing a suitable caravan which can be towed by any given vehicle legally, safely and comfortably.
This advice is supplemented by a complementary range of separate criteria which does need to be achieved to provide a satisfactory outcome.
I do indeed feel that at times the argument and counter argument about the validity of the 85% recommendation may confuse newcomers seeking advice but I'm not attempting to censor your challenges John or to 'tone you down'.
I'm merely attempting to show that the 85% recommendation is not the only factor to be taken into consideration by those seeking advice, no organisation has tried to claim otherwise, but your challenges appear to be based on the assumption that those forwarding the 85% recommendation believe it to be so.
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I think that if you read the texts carefully, they say that they test on the basis of the existing 85% recommendation, which I personally find less than helpful for those who choose to go closer to the manufacturers' specified limits. They do not say that they have carried out any tests to determine the relevance or otherwise of the 85%.
As for data from police, motoring organisations or insurers, it would be safe to say that none of these institutions have any such data, simply because the sample quantities are too small to allow any conclusions that could, in any way, be described as reliable. Although accidents involving caravans often make the headlines, this is mainly because they tend to be quite spectacular, but the actual numbers are too small to allow statistical differentiation of the weight ratios involved.
As for data from police, motoring organisations or insurers, it would be safe to say that none of these institutions have any such data, simply because the sample quantities are too small to allow any conclusions that could, in any way, be described as reliable. Although accidents involving caravans often make the headlines, this is mainly because they tend to be quite spectacular, but the actual numbers are too small to allow statistical differentiation of the weight ratios involved.
- Mar 14, 2005
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Hello Parksy
You are correct I do not have access to the police figures about the number of incidents where instability is considered a factor. But I suggest it is a reasonable contention that a significant percentage of incidents that involve the police do occur with outfits that are within the 85% guideline, But we must not forget all those incidents where the driver is able to recover from a wobble and so do not result in a complete loss of control or a collision.
I do concede that the major clubs do give additional advice over weight ratio, but even on the page Sprocket points to the major eye catching diagram is about 85%.
But yet again why 85%, why not 50 75 or even 100%. What is the basis of 85%.
I know that you didn't choose the figure so like the rest of us you can't argue for or against 85.
And there in lies the difficulty we all have, No one has any evidence of how the industry chose that specific figure, and the industry is keeping stum about it.
We could keep on trading reasons, but until the someone from the industry actually gives verifiable and validated reasons for the choice, I still question whether any actual testing was carried out to derive the figure. It also calls into question the validity of the figure for to-days cars and caravans.
You are correct I do not have access to the police figures about the number of incidents where instability is considered a factor. But I suggest it is a reasonable contention that a significant percentage of incidents that involve the police do occur with outfits that are within the 85% guideline, But we must not forget all those incidents where the driver is able to recover from a wobble and so do not result in a complete loss of control or a collision.
I do concede that the major clubs do give additional advice over weight ratio, but even on the page Sprocket points to the major eye catching diagram is about 85%.
But yet again why 85%, why not 50 75 or even 100%. What is the basis of 85%.
I know that you didn't choose the figure so like the rest of us you can't argue for or against 85.
And there in lies the difficulty we all have, No one has any evidence of how the industry chose that specific figure, and the industry is keeping stum about it.
We could keep on trading reasons, but until the someone from the industry actually gives verifiable and validated reasons for the choice, I still question whether any actual testing was carried out to derive the figure. It also calls into question the validity of the figure for to-days cars and caravans.
- Jul 15, 2008
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…….for what it is worth my thinking on this is exactly the same as Parksy’s.
The 85% maximum figure is just the starting point for drivers new to towing who often already own the tow car and have to match it to a caravan.
Those who argue against this figure should say what system they would favour instead.
Advising a new tower to choose ‘as light a caravan as possible’ would be too vague for drivers that would not be familiar with all the nuances of safe towing.
It is now 14 years since UK law has placed restrictions on the weight of caravan that can be towed by B licence holders unless they take a further trailer test.
Presumably this change was in recognition that drivers new to towing need to gain experience before towing heavier trailers.
The 85% maximum figure is just the starting point for drivers new to towing who often already own the tow car and have to match it to a caravan.
Those who argue against this figure should say what system they would favour instead.
Advising a new tower to choose ‘as light a caravan as possible’ would be too vague for drivers that would not be familiar with all the nuances of safe towing.
It is now 14 years since UK law has placed restrictions on the weight of caravan that can be towed by B licence holders unless they take a further trailer test.
Presumably this change was in recognition that drivers new to towing need to gain experience before towing heavier trailers.
Parksy
Moderator
- Nov 12, 2009
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Prof John L said:
Neither of us are competent to argue for or against the figure John but you have often argued against it or at least questioned it's validity.
Most casual enquirers use the 85% figure as a starting point from which to base safe towing practices upon.
If they come unstuck and fail to keep their unit shiny side up then it probably won't have been because of an incorrect weight ratio.
Both of our viewpoints are largely based on sets of assumptions, I'd consider it fair to assume that major caravan organisations base their data, which gives rise to their advice, on information or collective knowledge that they possess.
This information may or may not be in the public domain, those offering advice are under no obligation to reveal information that may be considered to be commercially sensitive so the person seeking advice must decide for themselves whether or not to accept the advice.
As far as many of us are concerned the reputation of these organisations is good enough to persuade us that their advice will be good (as opposed to bad or confusing) and therefore the advice is generally accepted except perhaps by engineers or those with an interest in science or engineering who are prone to questioning accepted practice.
Do you consider the 85% weight ratio recommendation to those inexperienced in towing to be bad or confusing advice?
When I was a muso we had a saying when rehearsing something new.
The saying was "It's close enough for jazz", in other words it may not have been note perfect but it worked!
The validity of the figure for today's cars and caravans may be said to constitute a separate debate because the information that any data would be based on would have to be retrospective for such information to be transposed into usable data.
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