Don't get me wrong...... but just why is the 85% tow match guideline continually perpetuated as a rule? see page 97 of the current "July" issue. It's NOT a rule, it's a good commonsense guideline, so come on PC, why do you put it in print as a rule? and perpetuate the myth that it is?
85% Rule??????!!!!!!!
- Thread starter GeorgeB
- Start date
Whilst reading P.C. I have never been left thinking that the 85% rule was anything but a guideline. P.C. have always explained it as such as far as I remember.
Marc
Marc
Hello George
I concur with the legality of your point, and whilst I also find it annoying and misleading, I do agree with the sentiment, that 85% is a sensible target guideline.
I concur with the legality of your point, and whilst I also find it annoying and misleading, I do agree with the sentiment, that 85% is a sensible target guideline.
I seem to remember when we first started caravanning some 34/35 years ago, one club recomended 75% and the other club recomended 80%, forget which club recomended which. Now they both go for the 85% recomendation, my outfit is at 77% of which I`m quite happy with.
Rule or good practice? when you hear that a caravan has gone walkabout on the M25 you start off by being glad it is not you. Then all the 85% rule/advice starts to be MY RULE OF THUMB. The fact is that as you become more experenced you might not etch it in stone but I would always be happier with a bit of tolerence.
While the 85% may be quite a good starting point, it is quite arbitrary. There is no real reason why it shouldn't be 80% or 90% and I doubt whether anyone can genuinely tell the difference how his or her outfit handles given a tolerance of up to 5% either way, all other conditions remaining equal. That doesn't mean to say that the tolerance can be exceeded regardless but there is no magic figure where everything below can always be considered safe but absolute certainty of impending doom as soon as you go over the so-called limit. There is a relatively big grey area of transition. Too many other factors also determine whether an outfit is stable or not. Under certain conditions they can even be more important than weight ratio.
good point lutz but as most opinion seems to differ as to the absolute max weight ratio and 85% rule of thumb seems quite universally accepted go with it.
as a caravanner of 30 odd years expierience I can usally guess as to how far I can go weight wise based on the tow car to be used.
before all the legal formuli was invented all you had to go on was your best guess, I dont know what it was like in germany? but in the uk we had a suck it and see approach it worked or not as the case may be.
I well remember trying to tow the old mans 16ft colchester with a 1300cc avenger to wales and only getting a far as chester before the engine siezed up. it wasn't a problem of weight ratio but the fact that the engine wasn't big enough, after ripping out the motor and replacing it with a 1725cc hillman hunter engine it towed fine @ about 120% weight ratio.
of course you would not get away with it today (or would you) after reading some of the manufacturers figures I wonder about that, take the max gross train weight from some cars kerb weight and you come up with over 100% max tow weight in some cases.
as a caravanner of 30 odd years expierience I can usally guess as to how far I can go weight wise based on the tow car to be used.
before all the legal formuli was invented all you had to go on was your best guess, I dont know what it was like in germany? but in the uk we had a suck it and see approach it worked or not as the case may be.
I well remember trying to tow the old mans 16ft colchester with a 1300cc avenger to wales and only getting a far as chester before the engine siezed up. it wasn't a problem of weight ratio but the fact that the engine wasn't big enough, after ripping out the motor and replacing it with a 1725cc hillman hunter engine it towed fine @ about 120% weight ratio.
of course you would not get away with it today (or would you) after reading some of the manufacturers figures I wonder about that, take the max gross train weight from some cars kerb weight and you come up with over 100% max tow weight in some cases.
There are loads of other factors - car loading, van loading and inherent stability of the car and van separately.
Smart cars, Suzuki Jeeps and some A class Mercedes have had stability problems solo so would probably make bad tow cars even at 50%.
My personal experience is a comparison between
Shogun LWB 2.5TD - heavy but with high centre of gravity and long travel soft suspension
And a
Seat Alhambra - lighter but much firmer suspension, wheel at each corner and lower centre of gravity.
Towing the same van the Alhambra was a much more stable towcar, and I am not even sure I would enjoy towing our present van with the Shogun.
This is not an attempt to relaunch the 4x4 debate again - I like 4x4s and there are definite circumstances where they can shine.
I also imagine a Hummer with its high weight and wide track would be unbeatable in terms of stability.
Just trying to point out that there is much more to stable outfits than straightforward weight ratios.
Smart cars, Suzuki Jeeps and some A class Mercedes have had stability problems solo so would probably make bad tow cars even at 50%.
My personal experience is a comparison between
Shogun LWB 2.5TD - heavy but with high centre of gravity and long travel soft suspension
And a
Seat Alhambra - lighter but much firmer suspension, wheel at each corner and lower centre of gravity.
Towing the same van the Alhambra was a much more stable towcar, and I am not even sure I would enjoy towing our present van with the Shogun.
This is not an attempt to relaunch the 4x4 debate again - I like 4x4s and there are definite circumstances where they can shine.
I also imagine a Hummer with its high weight and wide track would be unbeatable in terms of stability.
Just trying to point out that there is much more to stable outfits than straightforward weight ratios.
The instability of some towcars has nothing to do with their suitability or otherwise as a towcar. Solo towcar instability is based on their handling performance under much more severe conditions when taking avoiding action in case of a sudden hazard ahead. Instability of a car/caravan outfit, on the other hand, can occur even when travelling in a straight line. It all depends on how susceptible the car is to the 'tail wagging the dog' - something which of course doesn't occur when solo.
A car which very stable when solo can therefore still be a relatively poor towcar, and vice versa.
A car which very stable when solo can therefore still be a relatively poor towcar, and vice versa.
Lutz
So you agree with my basic argument about many other factors apart from weight ratio define what is a good outfit.
I still believe that a solo car with poor handling traits is not going to be as good a towcar as one with good handling traits.
I would rather tow a trailer with a Westfield 7 than a smart car (forgetting the power difference), I imagine the weight would be in the same "ball park".
Wider track, longer wheelbase,stiffer suspension and low C of G must be benefits to handling solo or as a towcar.
So you agree with my basic argument about many other factors apart from weight ratio define what is a good outfit.
I still believe that a solo car with poor handling traits is not going to be as good a towcar as one with good handling traits.
I would rather tow a trailer with a Westfield 7 than a smart car (forgetting the power difference), I imagine the weight would be in the same "ball park".
Wider track, longer wheelbase,stiffer suspension and low C of G must be benefits to handling solo or as a towcar.
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