Help required - towing weight

1  gross vehicle weight

2  gross train weight 

3  max front axle weight 

4  max rear axle weight

Google will help you.

Providing you don't exceed the axle limits, you can legally tow 2100kg (4235 minus 2135). However, that's a legal max and not a recommended safe or sensible limit for towing a large slab sided white box at 60mph down the M6 in a cross wind.

Take a look at your V5c and find kerbweight or mass in service and multipy this weight by .85 and will give you the clubs/ncc recommended van limit. there should be a sticker next to the door of caravan stating the Max weight the caravan can be and known as the MTPLM. Maximum Technically Permissible Laden Mass. Don't allow the caravan to be heavier than the vehicle thats towing it. 

The OP asked what the car can legally tow, not what is recommended.

Legally, anything can be towed so long as the combination is within the gross train weight and the car manufacturer's towload limits. If the car isn't fully loaded to its GVW of 2135kg, the car manufacturer may even allow a towload greater than 2100kg so long as the gross train weight limit of 4235kg is not exceeded.

Under item O1, the V5c should give details of the technical permissible maximum towable mass of a braked trailer.

I know that Lutz but I don't think he was asking a caravan forum if he can tow as much as his car is legally capable off. I'm taking it as if he already has or going to buy a caravan and is he safe to do so. I am sure you don't go over the 100% match even if your vehicle is capable of doing so. The V5 might give him the weight as you say but what about what licence he has, so the gross train weight will be wrong for him. He has asked this question twice so may get a different answer from you depending on how he asks it. 

The plated gross vehicle weight is irrelevant as far as driving licence restrictions are concerned. The 3500kg limit that applies to a Category B licence refers to the sum of the individual maximum allowable weights of the car and that of the trailer, not to the plated gross train weight, which could be greater than 3500kg.

There are plenty of people that tow even caravans at least marginally over a 100% weight ratio. It would therefore be wrong to flatly denounce such practice as being intrinsically unsafe although it does, of course, increase the demands placed on the driver, so one should carefully consider whether it can't be avoided.

Correction to the above

I should have said "The plated gross train weight is irrelevant as far as driving licence restrictions are concerned.", not "The plated gross vehicle weight is irrelevant as far as driving licence restrictions are concerned."

I know your an "expert" Lutz but at times you can get to technical.