Tow car

[Ty]

Hi All
Im am relitivly new to touring, but i have towed large traailers for work for the past 10 years, we bought a bailey pagent sancerre 2009 last year to see if we would take to caravaning and as we thought we have the bug , i currently tow with a 66 plate 316 auto bmw we have just looked at purchasing a Stirling continental 580 now this is were i get really confused the mass running order is 1534 kg and the mtplm is 1690 my new car comes in a couple of weeks bmw 4 series 318 d auto gran coupe with a max towing capacity of 1700kg if any could advise if the car will be ok to tow the continentle.any advice really appreciated kind regards Ty

 

[Ty]

Sorry 418d auto

 

[otherclive]

The makers towing capacity relates to the ability of a car to start a number of times on a specified incline. Also because if it’s shape and size a caravan isn’t an ideal trailer. A better gauge is to look at the cars kerb weight. A commonly used figure is that the caravan MTPLM should be 85% of the kerbweight. This is recommended for new towers but even experienced towers should not go beyond 100%. As you have experience a figure above 85% should be acceptable. As you will no doubt already know as well as the above weight ratio the way in which the van is loaded, driving style, road and weather conditions can all affect stability. So your best action is to find kerbweight.

None of my comments relate to the 418d engine performance in terms of torque or power. Also is the car as delivered fitted to tow as some BMWs required factory fitted cooler mods to support towing under warranty. To fit the mods after delivery was expensive. Your supplying dealer could advise.

 

[Raywood]

I agree with Otherclives post. Basically the MTPLM of the caravan should be less than the kerb weight of the car. Check if the manufacturers figure includes the driver and if not add 75 kg for that. Personally I would not go much over 90% although the BMW is generally regarded as a good tow car. There is no magic formula though for weights and the performance can vary with the combination and you cannot afford to get it wrong so err on the side of caution.
The towing limit is based on restarting five times on a 12% hill and is more about the strength of the driveline than safety.

 

[Ty]

Thanks for your replys guys , i think it may be a visit to BMW tomorrow ,on line the kerb weight is 1605kg but i have also found it at 1568 kg really fancied the continentle but its weight is around 1688kg i want to make sure the car is up to it and legal.
Thanks
Ty

 

[ProfJohnL]

Hello Ty
Just being "legal" is not what the others have been commenting on. it's "legal to tow up to the vehicle manufactures stated towed weight limit, but is it sensible? when you hauling a large box that becomes very sensitive to wind and other aerodynamic forces which can produce some quite surprising severe handling effects on tow cars.

The industry 85% guidance may just be blanket advice and not take into account any particular attributes a tow vehicle may have but it does follow the concept that caravans are not easy, they are difficult, and potentially troublesome, so keeping them as small and light as possible is a sensible thing to do.

Whilst this may not apply to your outfit, you must never exceed the tow vehicles load limits.

 

[Ty]

Thanks ProfJohnL , it looks like the caravans max weight is 83 kg over the cars kerb weight.

Thanks
Ty

 

[Lutz]

The towing limit is based on restarting five times on a 12% hill and is more about the strength of the driveline than safety.

Any self-respecting car manufacturer will not only check the car's ability to restart on an incline in order to determine its maximum towload, even though that's all that the regulations require. He will also take engine cooling and, braking performance as well as handling of the complete outfit into account. That said, the towload limit will always be a absolute maximum assuming the driver's ability to exercise appropriate due care and attention while towing, which may not necessarily apply to a novice.

Thanks ProfJohnL , it looks like the caravans max weight is 83 kg over the cars kerb weight.

Thanks
Ty

Where did you get details of your car's kerbweight? Published figures are always generic and are unlikely to agree 100% with the figure for your actual car. More often than not they are lower than actual data.

 

[ProfJohnL]

Thanks ProfJohnL , it looks like the caravans max weight is 83 kg over the cars kerb weight.

Thanks
Ty

Hello again Ty

There is great grey area around your situation, becasue firstly as Lutz has pointed out it is notoriously difficult to get accurate kerbweight figures, so any notion of the guidance being an iron clad indicator is out the window.

consequently the guidance is rather informal and should not be taken as a "you must" but more of a "you should" activity. It is based on a sensible approach of keeping trailers as small and light as is reasonably possible, and especially where caravans are concerned.

Just for clarity the industry guidance uses the calculation of trailer MTPLM divided by Kerbweight all times 100 to produce a percentage figure. This is a worst case scenario and in real life, the car will be heavier than its kerbweight, and the caravan may not be at its MTPLM. This will always give a real towing ratio less than the theoretical figure.

Is 83kg too much? well provided it still falls within the cars legal weight limits, then it really depends on the driver, A careful driver who has loaded the outfit carefully to minimise moments of inertia, could find such an outfit perfectly satisfactory to tow, but another driver who either loads it badly or tries to drive it like a sports car might come a cropper.

But it's also the case even if the legal weights are all ok, there's no guarantee that every trailers will work well with every tow vehicle, there are a few outfits that simply don't go well together regardless of who drives them.

AS an experienced driver I have towed many different combinations of caravan/trailer and car, as part of my employment and with fairly straight forward pre-flight checks, I have only had one instance where I felt I might have been loosing control. All were legal combinations weight wise, but some felt fine even with ratios in the order of 120%, and some with ratios as low as 60% have felt skitish.

Should you go for your proposed outfit? my inclination is to say its really marginal and perhaps you should be looking for a smaller caravan or bigger car to reduce the ratio.

 

[Raywood]

I understand what Lutz is saying, and yes the brakes and suspension should be up to the job, but I feel this misses the point as they are not that relevant to the main point here. To tow a caravan the towing vehicle must be heavy enough to control the caravan, and this is down mainly down to weight, although there are other factors involved. If the towing vehicle is not heavy enough then the outfit is potentially unsafe, and this is the point that I am making. No manufacturer claims anything other than the GTW is what it can tow rather than what it can tow safely.
Getting off safety though, I would have to say that in most cases towing at the maximum weight will mean the engine is at its limit and performance will probably be poor and fuel consumption high.
Kerb weights as the Prof says are often different to what the manufacturer says usually heavier and the only way to be sure is take the car empty to a weighbridge. You should also be aware that if it is heavier then your loading allownce will be less than stated.

 

[Lutz]

To put things a bit into perspective, the 85% weight ratio recommendation is unknown on the Continent, so many people there tow right at the limit, even if it is over 100%, and yet I can't say that I've seen more caravans littering the roads there than in the UK.

 

[ProfJohnL]

Hello Ray,

Every outfit is potentially unsafe, and there is no universal ratio figure that guarantee safety, and crucially it if there is a critical value, it will be different for each out fit, and is affected by road conditions at the time. For some the ratio figure might be very low, and others surprisingly high.

As for engines working at their limits, well that happens every time a car is accelerated hard, so its not really an issue or reason to artificially limit trailer weights to an arbitrary figure not defined by the manufacturer. Provided the GTW is not exceeded, the performance of the vehicle may not be sparkling but it will be adequate, and any engine working at high outputs the fuel consumption will always suffer, so these are not valid reasons for sticking to a fixed notional ratio value.There is no science that would confirm that 100% is the maximum ratio that must be adopted as a limit.

 

[Dustydog]

Check with your BMW Dealer. A lot of BMWs require upgrading of the water and oil cooling systems if used for towing.

 

[Ty]

Hi Gents

Thanks for all the replys they have been most helpfull , luckily i have a decent boss and transport manager after a bit of juggling i have swapped the car for a C220 sport which is more than capable of towing the caravan, hopefuly we will be buying the new caravan in tbe next week.

Thanks again
Ty

 

[xtrailman]

Its a poor match for a newbie, buy a lighter caravan.

 

[Ty]

Hi xtrailman
I am only a newbie to the caravan ive been towing hygiene units and other large units that are similarly sized to caravans for over 10 years i just want to make sure that we were safe and legal as the more i read up on the bmw the more i got conflicting data, i have had better info on here in 2 days than i have researched all week.
Thanks
Ty

 

[Anseo]

C220 sport has enough power I agree, weight ratio and lugability of accessories ???

Sports suspension, probably low profile tyres, sorry but you might want to consider a basic C220 (one that might be regarded as the 'wallowing' type).

A basic E Class 220 is a rather better option, night and day better (IMHO my experience).

Worth chipping in some £££s of your own towards the cost, test drive both and see how you feel about the comparisons.

Whatever you choose, I hope you have many and wonderful outings.

 

[xtrailman]

Hi xtrailman
I am only a newbie to the caravan ive been towing hygiene units and other large units that are similarly sized to caravans for over 10 years i just want to make sure that we were safe and legal as the more i read up on the bmw the more i got conflicting data, i have had better info on here in 2 days than i have researched all week.
Thanks
Ty

Towing over 100% ratio isn't advisable for an experienced tower either.
I did have one insurer who wouldn't offer cover for ratios over 100%, something else you should look into.

 

[Raywood]

Hello Ray,

Every outfit is potentially unsafe, and there is no universal ratio figure that guarantee safety, and crucially it if there is a critical value, it will be different for each out fit, and is affected by road conditions at the time. For some the ratio figure might be very low, and others surprisingly high.

As for engines working at their limits, well that happens every time a car is accelerated hard, so its not really an issue or reason to artificially limit trailer weights to an arbitrary figure not defined by the manufacturer. Provided the GTW is not exceeded, the performance of the vehicle may not be sparkling but it will be adequate, and any engine working at high outputs the fuel consumption will always suffer, so these are not valid reasons for sticking to a fixed notional ratio value.There is no science that would confirm that 100% is the maximum ratio that must be adopted as a limit.

Hi Prof, I do not think every outfit can be described as unsafe. A good stable combination is or should be safe provided it is driven sensibly. Every outfit has its limits but so does every car and on that argument every car is unsafe. As you have said the primary factor in driving is the driver.
Towing at the cars limits will normally give poor performance and lower weights provide a better driving experience. Towing does cost more in fuel but higher weight ratios cost even more is factual.
I accept that the 100% figure is not justified by any scientific evidence but a line has to be drawn somewhere and on what expert advice is available this is probably the best we can do. Based on what I have seen it is possibly too high and frankly anyone exceeding this is in my opinion reckless. I know you do like top play devil's advocate but even suggesting that a ratio over 100% might work to me is potentially likely to result in demonstrably unsafe outfits being on the road.

 

[ProfJohnL]

Ray, you should know by now that I pick my words carefully, I did not say that "every outfit can be described as unsafe" I specifically wrote "Every outfit is potentially unsafe" That is a very different implication to the one you have construed.

I do not specifically advocate that towing at 100% or more is to be encouraged, I am a firm believer that you should always try to keep trailer weights as small as possible, but that doesn't automatically preclude high percentages. I also suspect that if teh industry advice were to start to be used to enhance towing safety 85% may be considered too high.

The problem is the often used statement that when the caravan reaches 100% it starts to push the car is wrong because a caravan/trailer of any % ratio will impose additional thrusts into the tow vehicle it doesn't just start when 100% is reached. It is true that as the trailer weight increases the imposed loads on the car also increase, but there is no step change associated with 100%. There are plenty of towing vehicles (not just towing caravans) that are working at well over 100% its largely down to how they are driven.

As Lutz points out, The UK advice is not mirrored elsewhere.

 

[Parksy]

This thread has departed from the OP.
If forum users want to argue about finer details please start a separate topic to avoid drowning the good advice offered in a sea of semantics.

 

[Lutz]

Unfortunately, in the way the original post was written, it would seem fairly inevitable that the replies would drift off at some stage because there cannot be a cut and dried answer to the OP's question. There are so many other variables that also affect the end result that it will always be the subject of a personal opinion. There simply cannot be an unqualified answer to such a topic, unfortunate as it may be to the novice who would like something concrete to be able to work with.
It is so much easier when it's a matter of absolute limits which may not be exceeded under any circumstances.

 

[Parksy]

Unfortunately, in the way the original post was written, it would seem fairly inevitable that the replies would drift off at some stage because there cannot be a cut and dried answer to the OP's question. There are so many other variables that also affect the end result that it will always be the subject of a personal opinion. There simply cannot be an unqualified answer to such a topic, unfortunate as it may be to the novice who would like something concrete to be able to work with.
It is so much easier when it's a matter of absolute limits which may not be exceeded under any circumstances.

I completely understand your point Lutz, but in this case the O.P changed the parameters from what the consensus considered to be unsafe to a completely different towing vehicle.
The O.P appears to have been satisfied with the replies that he received since, so a further debate about ones choice of words is a departure from the O.P.
All forum members have equal status, new or old, and while advice based on experience is valuable there have been several complaints made about the perceived hi-jacking of threads when protracted forum debates which have very little to do with the O.P take place.
It has also been said that new members who ask what seems like a fairly simple question are scared away from continuing to use this forum when what appears to them to be a clique of longer term members hold lengthy technical discussions which can range far off topic on the thread started by the new member.
Nobody is trying to put a stop to debate or discussion, but these discussions need to be held on separate topics opened by those who take part.

 

[Dustydog]

I agree with a Parksy we should have a separate thread for further technical discussion.
What I don’t understand is why the rest of Europe has different ideas to us in the UK hmy:
Are the laws of physics different because Europe drives on the right hand side

 

[otherclive]

I agree with a Parksy we should have a separate thread for further technical discussion.
What I don’t understand is why the rest of Europe has different ideas to us in the UK hmy:
Are the laws of physics different because Europe drives on the right hand side

I think that apart from France and Belgium most of Europe is 50mph on all roads, although sometimes in Germany Ive seen vans with 100kph stickers, but I understand that these have to be subject to some regulatory and specification changes that wouldn't be feasible for a UK visitor.

So if the speeds are restrained to 50 mph the propensity of the unit to instability could be reduced all other things being equal. I once saw a German outfit pulling up the A46 out of Bath and was amazed that it was a large Hobby wider than UK vans were allowed at that time, and being pulled by a mid 2000's Passatt saloon. Its progress up the A46 was sedate to say the least.