Car towing limit

They do state that but I disagree with that as illogical in the same way as not to include any added permanent fixture such as a tow bar is illogical. I have no idea what was included when the original source 85% figure was determined way back when   

i want to be able to tow a twin axle van that is 1705kg fully loaded...

Then I think you would be well advised to choose another car but, as that's possibly not an option, maybe a lighter caravan!

I have towed at near 100% but one thing that I was never entirely sure of was the fully laden weight and your figure of 1705kg might quite easily be exceeded when, even if its spot on, you are still looking at something weighing a considerable amount more than the car.

You're right, it is a trifle illogical, but then the sources that make the recommendation shouldn't refer to kerbweight (which isn't documented anywhere), but to the actual weight of the vehicle. Otherwise, they should state the conditions under which the weight is determined.

Actual weight, by definition, includes all ex-works fittings, a 90% full tank and 75kg for the driver. It still wouldn't include the towbar if it was dealer fitted because the vehicle manufacturer wouldn't know about it when he documents that weight in the Certificate of Conformity. The only problem is that in the UK very few owners seem to be issued with that certificate, so the only option is for the owner to have the car weighed himself or to request a copy of the CoC.

the weight of the towbar fitted to any vehicle would come off the cars payload weight so kerbweight and max axle weight just like a caravan give your payload and would state the max axle weight on one of the door pillars or under the bonnet. anything added to car comes of your payload for that car,

Not sure that is anyway relevant to my post LL - well not for me anyway 

Kerbweight is not defined as an ex-works weight so it would increase if, for example, a towbar is fitted.

Correction should be 12.5% gradient. Regardless of the exact figure the manufactures towing limit is essentially to do with mechanical issues and not safe or sensible issues.

not your post Easy it's Amourers. thats why i didn't quote you

Basing towing load limits solely on the requirement to be able to perform a set number of restarts on an incline would shed a very poor light on any manufacturer. We certainly also carried out braking and handling tests to arrive at representative figures. That said, whether an outfit is safe or not, depends on adjusting one's driving to suit the conditions more than any absolute limit set by the manufacturer, because that limit only applies to ideal conditions.