Tow Weight Ratios

[SterlingWhiteRose]

I know about the "recommended" tow weight ratios, by the organisations, as the MTPLM of van being 85% of the car's kerbweight. However, is it just me, or when Practical Caravan do their tow car tests, they always refer to matching van and car, on this ratio, against the caravan's Mass in Running Order (MiRO).

Hence why the car's always seem to be pulling twin axles, when they don't have exceptionally high kerbweight.

Anyone else think this, or am I mistaken?

 

[ProfJohnL]

Haymarket have responded to this point previously.

When doing tow car tests, the magazines tend to borrow cars and caravans. So they tend to choose a caravan by it's MIRO, because it will be virtually empty.

As far as the tow car is concerned it cannot tell the difference between an empty caravan with a MIRO of 1250Kg or a loaded caravan with an MTPLM of 1250kg.

 

[SterlingWhiteRose]

Guess that makes sense, but, it's not very "real world", as I'd expect to see car pretty well loaded up, and van moderately loaded. I'm sure they could still load a van when it's hired.

On top of that, I've seen on their tow tests they load the vans with ballast, made up of water containers.

 

[ProfJohnL]

I wonder if you are getting confused between individual tow car reports and the tow car of the year tests?

At tcoty tests they have a lot of cars and few caravans, so they need lots of ballast available to ensure they can arrange the optimum towed weight for each car.

For the individual reports, which don't go into the same detail as the tcoty, they can choose a caravan usually from dealership which most closely matches the weight criteria determined by the car. Some ballast may well be used to set the correct nose load.

As I previously hinted, the car cannot tell what it's towing, it only reacts to its mass and it's distribution.

 

[Woodentop]

Do also remember that 85% is just a recommendation that someone plucked out of the air for the sake of the safety of newcomers to towing.

An experienced tower doesn't even worry if the load gets to near 100%.

 

[SterlingWhiteRose]

Hi Woodentop, thanks for that.

I currently pull at 93% and never had any issues or felt particularly uncomfortable. Been towing 2 years now. But new van is coming shortly and kerbweight to MTPLM will be at 100% almost exactly. Van will have AL-KO ATC if that makes any difference also ha ha. I'm not overly veneered as to be honest, as mentioned before, car is always well over kerbweight and van shouldn't reach the MTPLM at all as don't put MUCH (I accept stuff adds up).

That said, am looking to get a new car soon, so was thinking to increase kerbweight.

 

[ProfJohnL]

Hello Sterling,

You have a quite pragmatic approach to towing and thats great to see.
As Woodentop reminded us the recommend towing ratio's are just that recommendations, and as they have no legal basis no one is going to be prosecuted for exceeding them, provide the weight of the caravan is still within the tow vehicles towing capacity.

You are also right to point out that cars when loaded will be heavier than its kerb weight, so the real world towing ratio will always be better than the worst case specification derived figure. But I must point out that even with a lower real world ratio, that still does not guarantee a good towing match, which is why I am always circumspect about using these recommendations, but in the absence of a better way that is easily understood and calculated, they are better than nothing.

Again I'm inclined to think Woodentop is right about the way the figures were chosen, because if it were possible to know the towing ratio's of all towing incidents where the stability of the outfit was a factor, I'm confident that we would see a large percentage of such incidents occurred with calculated ratio's of less than 85%, which calls into question the efficacy of the recommendation.

However I should not ignore the fact that weight ratio's are not the only factor involved with good and safe towing, All the other weight related criteria such as node (Edit) noseload, and load distribution, needs to be considered, along with the mechanical condition of both the tow vehicle and trailer. Road and weather conditions also must play a part, but I'm inclined to think the driver has the biggest part to play in such things. Driving style and top of the pile speed both of which are in the hands of the driver.

 

[Woodentop]

One thing not mentioned that is vitally important is noseweight.

You vehicle handbook will tell you the maximum hitch loading - typically somewhere around 80Kg - and the towbar or its handbook or attached label will tell you what the bar can handle. Which ever is the lower is the LIMIT and must not be exceeded.

My last car - a Passat estate which has one of the highest towing limits around - was rated 90Kg, but the Thule removable hitch towbar was rated 85Kg, so 85Kg was the limit. My current Passat estate has a Westfalia hitch and that is rated 90Kg like the car so that is what I can use.

It does not follow that because the hitch is high rated you can use anything lower. It is generally accepted that the higher the hitch load up to limit the more stable the tow will be - but nonetheless running a few Kg under never hurt anyone.

If you are towing with something - e.g. a 4x4 or large van - that has a hitch load of over 100Kg remember that the hitch limit of an Al-Ko chassis is 100Kg - you will find it in the book - and that must NEVER be exceeded.

 

[ProfJohnL]

One thing not mentioned that is vitally important is noseweight......

Yes I did, well almost :huh: I accidentally wrote "node load" by mistake Should have been Nose Load.

 

[Raywood]

Hi Woodentop, thanks for that.

I currently pull at 93% and never had any issues or felt particularly uncomfortable. Been towing 2 years now. But new van is coming shortly and kerbweight to MTPLM will be at 100% almost exactly. Van will have AL-KO ATC if that makes any difference also ha ha. I'm not overly veneered as to be honest, as mentioned before, car is always well over kerbweight and van shouldn't reach the MTPLM at all as don't put MUCH (I accept stuff adds up).

That said, am looking to get a new car soon, so was thinking to increase kerbweight.

Having been the man who investigated the accidents, I would not even consider towing at 100%. I have had to deal with the results and I know what can go wrong. I cannot accept that having towed at any particular weight ratio for two years gives you the experience needed to assess the risks. Quite simply in that period you are unlikely to have experienced the severe conditions that can happen which test your outfit to or near the limit. My firm advice would be to abandon any idea of towing at 100% as it is simply unlikely to be a safe outfit although there may be the odd combination tha works but you cannot be sure of yours.
I know when actually using the caravan the car will be loaded and exceed its kerb weight but that was the case whan the 85% figure was suggested and was taken into account. I also accept that design has improved since then and it can be exceeded to some extent but not to the extent you suggest.

 

[SterlingWhiteRose]

I take your point entirely, and this is the reason I am looking to change to something heavier.

It doesn't help however, that the retailers, manufacturer (Swift) and PC Magazine, all show different specified weights for the vans MTPLM! Swift having used it after my purchase and stating it is a mistake between their literature and website.....well that's ok then huh!

I am likely to purchase a new medium size SUV and tow weight ratio likely between 83% and 95%.

I'm always welcoming of "advice" on here, but "lectures" and misinterpretations I'm not so keen on. I wasn't suggesting I'm an overly experienced tow-er, by having towed for two years, I was merely stating the period I had been towing!

 

[Hutch]

Welcome to the Forum, don't read to much " critisim" into replys , the majority of people are trying to help. Just a little bit about the Al-Ko ATC system as others have said, hopefully people adjust their driving so as to never have to be aware the system is working.
I will admit to having gone past a lorry on a hill on a gusty day and just as the van past the lorry, the van got into the biggest snakeing, I have ever felt, for about 3 to 4 seconds I didnt know what to do. Accelerate, brake, or clean my pants. Suddenly the van braked on its own pulled us straight and we slowed to about 55 mph. So the system does, work, just be aware, its a help, not a unit you should rely upon.
Safe touring.
Hutch.

 

[ProfJohnL]

I'm sorry for trying to help you with your query

Please don't forget that we have absolutely no idea what your skills, experience are, so unless you tell us we can't mind read. Also, some please bear in mind that some of us do have in depth knowledge and may be aware of detail, which may explain the reason an activity or answer is not as simple as you might expect.

I believe it is better to be given more information, and perhaps discard some rather than not been given enough. Also whilst an individual asks a question, there could be others who perhaps were wondering the same thing, but had not plucked up the courage to ask. So while we should attempt to answer the prime question, additional information may help others.

 

[WoodlandsCamper]

...and misinterpretations I'm not so keen on. ...

Misinterpretations will only occur if the original statement was not explicit enough for people to understand correctly.

 

[Raywood]

I am not trying to be overcritical but passing on what I have learned from an angle most people cannot get. Personally I would not want to go above 90% but with the right tow car it could be posdible. The problem is you cannot try out the combination before buying so a cautious approach is I feel the best way forward.
I tow at 96% and this has generally been very stable with only one incident involving a Post Office armoured van passing me at a very high speed causing any real movement. I have towed nearer 90% without problem though.

 

[JonnyG]

i get where you are coming from Raywood, but what about ability, natural ability. now I've rode bikes on and off for coming on 40 years did a little proddie racing as a kid, numerous track days ect ect ,but my old friend still had superior natural ability where motorbikes where concerned. lately we;ve had some huge down pours and i;ve been on the road in a 15 tonne lorry and amazed at how fast everyone was still driving..yet i'd wager a few pounds the vast majority on a track could not stay anywhere near me.. so what about natural ability? all the experience in the world might not be enough to avoid an incident when towing at 100% where as natural ability maywell be enough? just a thought, experience does not necessarily make you the better of someone with natural ability for want of a better word.

 

[Raywood]

i get where you are coming from Raywood, but what about ability, natural ability. now I've rode bikes on and off for coming on 40 years did a little proddie racing as a kid, numerous track days ect ect ,but my old friend still had superior natural ability where motorbikes where concerned. lately we;ve had some huge down pours and i;ve been on the road in a 15 tonne lorry and amazed at how fast everyone was still driving..yet i'd wager a few pounds the vast majority on a track could not stay anywhere near me.. so what about natural ability? all the experience in the world might not be enough to avoid an incident when towing at 100% where as natural ability maywell be enough? just a thought, experience does not necessarily make you the better of someone with natural ability for want of a better word.

To drive safely you need a safe outfit. The simple fact is that if the trailer is too heavy for the towing vehicle no matter how skillfull the driver it can take control and possibly cause an accident. The laws of physics cover this and ignoring it makes no sense.
I am sorry but those who feel natural ability will save them have met me before when they were proved drastically wrong.

 

[ProfJohnL]

i get where you are coming from Raywood, but what about ability, natural ability. now I've rode bikes on and off for coming on 40 years did a little proddie racing as a kid, numerous track days ect ect ,but my old friend still had superior natural ability where motorbikes where concerned. lately we;ve had some huge down pours and i;ve been on the road in a 15 tonne lorry and amazed at how fast everyone was still driving..yet i'd wager a few pounds the vast majority on a track could not stay anywhere near me.. so what about natural ability? all the experience in the world might not be enough to avoid an incident when towing at 100% where as natural ability maywell be enough? just a thought, experience does not necessarily make you the better of someone with natural ability for want of a better word.

To drive safely you need a safe outfit. The simple fact is that if the trailer is too heavy for the towing vehicle no matter how skillfull the driver it can take control and possibly cause an accident. The laws of physics cover this and ignoring it makes no sense.
I am sorry but those who feel natural ability will save them have met me before when they were proved drastically wrong.

Hello Ray,

I understand the point you are making, and agree that simply relying on the seat of your pants to control your driving is not a safe mind set. But I cannot agree with your generalisation about, "if your trailer is too heavy" and the assumption a 101% tow ratio is therefore too heavy.

I must make it clear when I refer to "tow ratio" that is MTPLM/ULM, and weight ratio is real caravan weight/ cars real weight.

Setting the legal side of this to one side at the moment, and simply looking at the mechanical side, we know a calculated 100% tow ratio is not a true 100% weight ratio, as the calculation fails to take any load in the car into account. So for example if a car with a ULW of 1300kg were coupled to a caravan of MTPLM 1300kg we would say that's a 100 % tow ratio. But in reality the car could have a GVW of 1700kg and if it and the caravan were both fully laden the actual weight ratio would be 1300/1700 which is only 76%. If the caravan were not fully laden the weight ratio would be even smaller.

So by saying that a 100% tow ratio a " no no" you could easily be condemning a real world weight ratio as low as about 70%!

This just goes to show how misleading the tow ratio figures can be. Now I am not advocating everyone should start recalculating their tow ratio's, because that would be whole impractical, as it would mean actually weighing your outfit on every trip. Nor am I advocating caravanner's should feel any safer with approaching 100% tow ratio's, but I do think this black and white approach of '100% tow ratio s OK but not recommend but 101 or more spells disaster' is not realistic.

I have perviously suggested how unsatisfactory I find the very specific nature of the current tow ratio guidace is, as it gives the impression of an authoritative body proffering safety advice, which we know and has been demonstrated not to be the case.

In practice we know that incidents of caravan instability occur all the time, some go on to involve the driver loosing control, and that must mean a significant proportion of those serious incidents must involve outfits that have observed the tow ratio guidance, which leads to the inevitable conclusion should we be reevaluating the guidance down from 85?

 

[Raywood]

I do accept that the 85% ratio could be updated a bit but when this was formulated it was well known that the car was never going to tow at just its kerb weight so some allowance has to be in there for it being loaded to some extent. On hat basis I do not feel you can rely on the additional weight of the cars contents to adjust the ratio. Drivers should also be aware that some car insurance policies actually exclude cover if towing a trailer exceeding the kerb weight of the car. That exclusion can only have come about as a result of those companies having a problem with claims where this was present.
From my point of view it is just plain stupid to tow at or near the kerb weight and I have met those who tried and failed.
I was not happy when on site last week when I saw a Pegasus Verona being towed by a Yeti, at best this was probably 100% although depending on exactly which version the Yeti was it was it could have been worse.

 

[JonnyG]

i get where you are coming from Raywood, but what about ability, natural ability. now I've rode bikes on and off for coming on 40 years did a little proddie racing as a kid, numerous track days ect ect ,but my old friend still had superior natural ability where motorbikes where concerned. lately we;ve had some huge down pours and i;ve been on the road in a 15 tonne lorry and amazed at how fast everyone was still driving..yet i'd wager a few pounds the vast majority on a track could not stay anywhere near me.. so what about natural ability? all the experience in the world might not be enough to avoid an incident when towing at 100% where as natural ability maywell be enough? just a thought, experience does not necessarily make you the better of someone with natural ability for want of a better word.

To drive safely you need a safe outfit. The simple fact is that if the trailer is too heavy for the towing vehicle no matter how skillfull the driver it can take control and possibly cause an accident. The laws of physics cover this and ignoring it makes no sense.
I am sorry but those who feel natural ability will save them have met me before when they were proved drastically wrong.

nobody mentioned anything about breaking the law by towing illegally . dare i say to drive safely you need far more than merely a safe outfit.! a gun in a draw is harmless but take it out and you have a deadly weapon .same with towing no such thing as a safe outfit once its not parked on the drive way and a human takes charge it is only as safe as the person in charge experienced or not.....I believe you missed my point entirely. . I wager a bet you have met many who thought they had natural ability, the key word being "thought" its no different to using the term Experienced , what exactly does that mean?..maybe i used the wrong terminology in using "natural ability" my point was you cannot assume an experienced caravaner has some god given right to be safer when towing than someone, one would term a novice....Ability at anything plays a part what makes you think towing safely in part doesn't involve a persons Ability novice or not....

 

[ProfJohnL]

I do accept that the 85% ratio could be updated a bit but when this was formulated it was well known that the car was never going to tow at just its kerb weight so some allowance has to be in there for it being loaded to some extent. On hat basis I do not feel you can rely on the additional weight of the cars contents to adjust the ratio. Drivers should also be aware that some car insurance policies actually exclude cover if towing a trailer exceeding the kerb weight of the car. That exclusion can only have come about as a result of those companies having a problem with claims where this was present.
From my point of view it is just plain stupid to tow at or near the kerb weight and I have met those who tried AMD failed.
I was not happy when on site last week when I saw a Pegasus Verona being towed by a Yeti, at best this was probably 100% although depending on exactly which version the Yeti was it was it could have been worse.

Hello Ray,
Just to be clear, I have not suggested you should use the additional weight in the car to increase the towed load, far from it, I am suggesting that despite the additional load which does infact reduce the weight ratio, there have still been incidents, which shows how misleading the guidance can be. But it is the best we have at the moment.

Just as a note, the CC in number of publication has actually referred to the measured weights being used to calculate the ratio, but as no one can easily establish real loaded weights it's impractical.

Is it plain stupid to tow at kerb weight? I guess it is if you have an incident, but I'll wager that for every person you have met there will be many more for whom there has been no drama. I don't condone it, as I have always advocated keeping the towed mass as small as possible, but it is possible .

The biggest draw back of the way the guidance is used and perceived is it only relates to one aspect of outfit . It should also highlight the importance of nose load, vehicle maintenance and driving habits.

 

[Plodd]

I was not happy when on site last week when I saw a Pegasus Verona being towed by a Yeti, at best this was probably 100% although depending on exactly which version the Yeti was it was it could have been worse.

I have only just joined the forum and have never towed although I was a Police traffic officer driving cars and riding bikes so i'm not a novice driver. I have a Yeti and was quite worried about caravan weights before I bought one. Although a 4X4 as i'm sure you know from your comment I quoted the Yeti is not very heavy. I finally chose a Sprite Freedom 6 which appears to be a match of well under 80%. It has been a confusing pain to find that out though as Skoda quote kerb weight without a driver. Some of the online matching sites take this into account but some do not. A very confusing topic for the novice such as myself.

 

[ProfJohnL]

Hello Plod, and welcome to the confusing world of towing weights and loads.

I do hope you will feel able to add your perspective as a retired traffic officer

 

[Raywood]

Have to agree with Plod, the subject is very confusing even for those of us who have towed for years. My advice is always err on the side of caution.