Hello Gary,
There are several sites that offer matching advice, but you have to use them very carefully.
Basically either they do not carry the specific information for your exact model of car or caravan, or the information they do may be inaccurate.
If they do not have your exact model of car/caravan in their lists do not be tempted to use what might seem a similar model, as each make and model has its own specification, and similar models may actually be quite different.
Either way, its is not difficult to do the actual calculations once you have the required information. - you certainly do not need to pay a web site to work it out for you.
Legally the driver is responsible for the roadworthyness of their car/caravan, If the outfit is matched incorrectly saying you relied on a web site to work it out will not be a defence.
, and you have know way of knowing which is
, because several sites are known to have ommisions in th