Ball Weight

[Nick_5041176]

Can anyone explain why the Caravan Club recommend that the ball weight should be 7% of the loaded weight of the caravan but proceed to test vehicles less than that. I am confused by recommendations based solely on the tow vehicles weight?

 

[Lutz]

If you apply the 7% formula to any caravan weighing more than 1071kg the towball load would exceed 75kg which is the maximum permissible figure for a good many cars. Except for 4x4's there are relatively few cars on the market where a towball load of over 75kg is allowed. However, quite a lot are perfectly capable of towing more than 1200kg, so in such cases, the towball load is limited to the maximum permissible, i.e. 75kg regardless of any 7% formula.

 

[Mike_5041089]

There are two main issues when matchng car & caravan:-

The 'van should not exceed 85% of the tow car's kerbweight, and the tow bar download must not exceed the car maker's maximum, normally 75kg, as Lutz says. Established wisdom states that ideally a 'van should have a 7% towbar download of its MTPLM, but it is ok to tow with a lower noseweight, provided you load sensibly. Place any heavy items over the axle & get yourself a noseweight gauge.

 

[ProfJohnL]

I am not sure exactly how the 85% tow weight and 7% nose weight guidelines came about, but I suspect that at some point in the dim and distant past some one carried out a survey and found that caravanners began to have disproportionately more problems with stability when the 85% and 7% figure were exceded, and so these figures have passed into folk law. Some elements of these figures have been embeded in to statutes, but how relevant these figures are to-day with modern cars and caravans is perhaps uncertain. Despite my comments 85% is still a practical figure, and most outfits conforming to it are generally trouble free - but there are always exceptions, and loading and driving techniques can be highly significant.

 

[Lutz]

I fully agree with you, John, but I would have thought that owners are just as likely to notice a problem if they have significantly less than 7% towball load rather than if they exceed it. Both extremes can detrimentally affect the stability of the outfit.

 

[WatsonJohnG]

Agree (as usual) with Lutz.I always try for the heaviest nose weight below the max allowed for the car.