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willow11

Tugging And Pulling When Towing - Help?

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So - I’m after some advice please. I’ve a 2014 Mercedes E class estate (7 speed tiptronic auto) e220, and am towing a new Lunar Quasar 586. We’re brand new to it, I’ve never towed with any other combination.



Car to van ratios are fine, it’s around 71%, nose weight around 90kg (the mercedes is listed at 84kg but I’m new and I’m struggling to get it that low), and am well within GTW of around 4450 kg.



I’m getting a really pully, tuggy type ride, usually on the 40 mph type A roads. Motorways at 50mph I don’t notice it, but as soon as I leave the motorway then it’s not smooth at all, car jerking and even my wife remarked what a terrible road surface it was - but the surface was fine, it was the towing.



I’m stuck. There’s not much extra in the van (payload is 175kg and even if I’m pessimistic there’s only 100kg added in). Oddly, another caravaner asked me last week what the ride was like and whether it pulled and tugged. I said it did, and he told me he towed with an A4 tiptronic box that was horrible; he never realised how bad it was until he changed his car.



Any ideas? Or is it normal?



Cheers!


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Check you car handbook for M-B's advice on tyre pressures for towing, often using the full load pressures but makes/models do vary.

 

Make sure the hot water system is drained down before each tow, that'll take 8-9 kg off your noseweight - use bathroom scales under the jockey wheel (with wood to spread the load) to measure the noseweight with the hitch at towball level, there's a slight geometric inaccuracy in that method but many noseweight gauges are very inaccurate.

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Good advice from BG and you may find that you're being optimistic with your estimate of actual payload.

 

If the max. payload is 175kg as you say and you have a mover fitted then balance of payload is around 135kg and if you have a 110a/h battery installed then the balance is down to 110kg. If you put your awning in the van then the balance is down to about 70kg. Each person's clothes about 15kg, each set of bedding about 5kg, Aquaroll and Wastemaster 15kg, a few bottles of drink and the frdge contents 15kg, 6 towels 5kg, cutlery, saucepans, plates 6kg it all mounts up very, very quickly.

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Thank you. .



I’m using the Milenco nose weight scale - the only thing is I’ve never managed it without being onto gravel, but I try and kick all the lose stones away to get the scale onto compact ground. If I put a piece of 4x1 under then that evens it out, and reduces the nose weight reading by around 5kg.



The mover is 30kg, then I’ve allowed 20kg for the battery, 25kg for awning, 15kg for Aquaroll and Wastemaster, 5kg for bedding, 5kg for plates and 5 for pans (we’ve only the minimum lightweight stuff). We don’t stores clothes or food /drinks. Ok - that’s 105kg (good point!), but I use Calorlite not the 16kg bottle allowed in MRO, and I make sure everything inc toilet is fully drained. Was thinking of a weigh bridge but I still think I’ve a fair bit off 175kg payload.



Tyre pressures are correct for the fully laden car as given on the door pillar (there’s nothing extra in the book on special towing pressure)…

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You've got plenty of things there that you can move rearwards to get the noseweight below the rig's limit and it can be v surprising what a difference it makes. As said elsewhere shifting the EHU cable from gas locker to the rear reduces the noseweight by circa 10kg.

 

I now put all the small heavy stuff in two folding plastic crates in the back of the Volvo. One crate has stuff I might use and the other has stuff I know I will use whilst setting off and pitching on site. So, wheel lock, hitchlock, electric drill for steadies, winder handle, awning pegs, peg hammer, dog tie-outs etc. They come to a fair old weight, in fact I can't lift the two together. The one I know I will use is kept accessible by the Volvo's hatch door, the other one is tucked away.

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I tow with audi tiptronic box,no issues once the tyre pressures were set right.

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I suspect that you don't actually have a problem. All vans pull and tug a bit even with minor undulations. I am sure you will get used to it.

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I would check that the ATC isn't operating, and that the drawbar is lubricated.

Sounds brake related?

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Do you have a retractable or swan neck towball or a fixed towball?

If retractable or swan necked have you cleaned all the paint or coatings (zink etc) from it, to leave clean steel,

If fixed have you got an AlKo type towball, this must be cleaned of paint

I would also be tempted to check the AlKo hitch pads in case they have any grease on them (usually courtesy of the dealer),

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Willow, I had an e250 estate (late 2013 facelift model). Never found it very stable as a towbar and after a close call I eventually got rid of it as the whole rest of the car lofted whilst towing past a lorry on the m5.

 

Loading in the car is very sensitive (and I mean really sensitive). Critical that you get the nose weight down to around 80kg. Then load the car in a very specific way - that way I mean all heavy items sat right at the back of the boot over the rear axle of the car. Only put very light items in the rear of the boot near the boot door.

The other thing to look for is the brand of tyres. Originally the car would have come with continental tyres. I changed mine once to Michelin on the rear and the car became unstable to tow with. When the fronts to backs were switched round with continentals at the back it became a lot more stable again. Make sure they are the xl loading on them too.

 

In the end I got rid of mine as I didn't want to chance towing issues post episode with lorry being down to one brand of rubber v's another.

 

Drop me a PM if you need any more help in loading options or advice as happy to help

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I used to have a Mercedes 320 CDi auto saloon and had the same problems. Plenty of weight and power but they are not very comfortable tow cars.

 

Bob

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I am going to disagree about rear tyre pressures.

 

The max loading tyre pressure is for exactly that. The CAR being loaded to its max.

 

think three Americans in the back seat plus all their luggage in the boot, about 400Kg?

 

Now if you attach you caravan to the tow hitch and it has a nose weight of say 75kg, if you take into account the leverage effect that will add ONLY about 100kg to the rear axle loading and that is WAY below the vehicles maximum load, therefore you should NOT inflate your rear tyres to the pressure advised for a full load because, for the reasons given, your car is not fully loaded. Overinflated tyres will give a very harsh and bouncy ride!

 

Andy

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I am going to disagree about rear tyre pressures.

 

The max loading tyre pressure is for exactly that. The CAR being loaded to its max.

 

think three Americans in the back seat plus all their luggage in the boot, about 400Kg?

 

Now if you attach you caravan to the tow hitch and it has a nose weight of say 75kg, if you take into account the leverage effect that will add ONLY about 100kg to the rear axle loading and that is WAY below the vehicles maximum load, therefore you should NOT inflate your rear tyres to the pressure advised for a full load because, for the reasons given, your car is not fully loaded. Overinflated tyres will give a very harsh and bouncy ride!

 

Andy

Due to previous issues with my merc I experimented with various inflation levels. It was less unstable at the full load. Just bear in mind that op said 4 of them plus luggage and 80kg of van. Seems pretty loaded to me

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Funnily enough Volvo describe the maximum load tyre pressures as a 'Full Load Pressure' and 'ECO Pressure' where the most favourable fuel economy will be achieved. However it then goes on the say that below 160KPH the 'General' tyre pressure should be used for both light and full loads. So it seems to be saying use the 'General' pressure unless you're going to drive at over 100mph, which plainly you won't whilst towing.

 

However when towing people normally put fairly heavy items in the boot of a car, rather than in the caravan, due to a van's very limited payload. On our last trip I calculated the car's payload was just over 400kg, including the caravan's noseweight and the payload limit is 472kg. So quite near the limit and certainly enough to qualify as heavily loaded.

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I am going to disagree about rear tyre pressures.

 

The max loading tyre pressure is for exactly that. The CAR being loaded to its max.

 

think three Americans in the back seat plus all their luggage in the boot, about 400Kg?

 

Now if you attach you caravan to the tow hitch and it has a nose weight of say 75kg, if you take into account the leverage effect that will add ONLY about 100kg to the rear axle loading and that is WAY below the vehicles maximum load, therefore you should NOT inflate your rear tyres to the pressure advised for a full load because, for the reasons given, your car is not fully loaded. Overinflated tyres will give a very harsh and bouncy ride!

 

Andy

Many car makers ADVISE using the high load pressures when towing - you think they're wrong do you ?

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Many car makers ADVISE using the high load pressures when towing - you think they're wrong do you ?

I totally agree BG, that advice often features a schematic showing two people in the car as a 'Low' load and five in the car as a 'High' load. That's obviously not exclusively linked to just passengers, but can be 'stuff' as well. It must be fairly rare for a caravan to be pulled by a lightly loaded car and the noseweight just increases the probability that it's highly loaded in normal caravan towing circumstances.

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Car manufacturers START tyre pressure evaluation by calculating axle loads vs tyre load capacity BUT then go on to spend 1,000s of hours on a test track honing the tyre pressures to give the optimum compromise of grip and ride, based on their perceived customer base - so it's not all about load variations.

 

I've had cars in the past where the car makers advise is to increase front tyres pressures by 4psi for "sporty" driving - nothing to do with load, but to do with grip - so it doesn't surprise me one bit that they often recomment increasing tyre pressures when towing (even if the car has no extra load).

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Many car makers ADVISE using the high load pressures when towing - you think they're wrong do you ?

I tend to agree with plod.

 

Just pumped my car tyres up today, I've only put 40psi into the rears as I'm not on full load, full load needs 42 psi.

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I tend to agree with plod.

 

Just pumped my car tyres up today, I've only put 40psi into the rears as I'm not on full load, full load needs 42 psi.

That's your call. I don't always follow handbook advice but I understand why they make it.

 

I sometimes (nearly always) play around with solo pressures, going up from handbook figures, to get the compromise of handling and grip that suits my style of driving - never going down though.

 

As I posted earlier, load requirement is just one aspect.

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I always run 2 psi over the recommendation when driving solo myself at 38psi.

I've also towed with less than 40 psi with no detrimental affect on towing, as low as 38psi.

 

36psi is for "normal loads"

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I always run 2 psi over the recommendation when driving solo myself at 38psi.

I've also towed with less than 40 psi with no detrimental affect on towing, as low as 38psi.

 

36psi is for "normal loads"

How do you test for "detrimental effect" - normally, we all try to avoid the extreme circumstances where detrimental effects start to show.

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Are you serious?

 

Or have we now reached the "nit picking" stage.

As the dragons say I'm out.

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Our Kuga certainly towed better on undulating roads or rougher sufaces when the tyres were inflated to 'max load' pressure. Quite a difference in fact.

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Funnily enough Volvo describe the maximum load tyre pressures as a 'Full Load Pressure' and 'ECO Pressure' where the most favourable fuel economy will be achieved. However it then goes on the say that below 160KPH the 'General' tyre pressure should be used for both light and full loads. So it seems to be saying use the 'General' pressure unless you're going to drive at over 100mph, which plainly you won't whilst towing.

 

However when towing people normally put fairly heavy items in the boot of a car, rather than in the caravan, due to a van's very limited payload. On our last trip I calculated the car's payload was just over 400kg, including the caravan's noseweight and the payload limit is 472kg. So quite near the limit and certainly enough to qualify as heavily loaded.

On my V60, they now have eco and max load pressure the same value.

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On my V60, they now have eco and max load pressure the same value.

 

That's what I said in my first sentence Ian.

 

Since writing the above I've checked the 'Towing' section of the V70 handbook and there it does suggest adopting the max load pressure/Eco pressure for towing. However the 'Tyres' section of the handbook is as I stated above and appears to suggest not adopting max load pressure/Eco pressure unless you're going to exceed 100mph solo.

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