Your towing vehicle unladen weighs 1,700Kg therefore your trailer cannot weigh more loaded than 1,700Kg making a total of 3,400Kg. However you may find that this exceeds the trailer weight recommended by the vehicles manufacturers and as soon as a driver and passengers get in the tow car, the MAM exceeds 3,500Kg
If a Nissan Almera has a maximum kerb weight of 1,253Kg yet the manufacturers tell us our loaded trailer/caravan must weigh no more than 1,200Kg. A heavier car will tow more, however if the towing vehicles gross weight (including occupants) is 2,500Kg the trailer must weigh no more than 1,000Kg loaded making the total 3,500Kg. Therefore getting the right tow vehicle and trailer combination can now be a very difficult thing to achieve, as many caravans are in excess of 1,300Kg unloaded.
If you wish to exceed any of the above weight limits, then there is no alternative for drivers with only a Category B licence to take and pass the additional test (B+E). If you have a licence including category B+E you can tow any trailer up to 3500kg, provided that you don’t exceed the vehicles towing limit and the MAM of 8.25tonnes. Also the weight shown on the trailer plate is taken into account (the gross maximum).
With your B+E licence it is what you are actually towing that really matters. In other words, if the trailer plate shows a figure higher that the car’s maximum towing limit thats ok provided that you are actually towing a lesser weight.