The majority of motor caravans come to the market rated at 3,500kg GVW to meet the requirements of the market segment made up of drivers who only possess a Category B Driving Licence.

However, more often than not there is an optional extra available to have an 'uprated' GVW at the time of delivery. This option is usually availed of by those lucky enough to possess a category C1 licence (or higher).

As motorhomes find their way onto the used market their existing GVW rating may not meet the needs of some secondhand buyers. B Licence holders may wish to own a particular vehicle but are unable to do so because it has perhaps been uprated to 3,850kg GVW or a higher figure.

Similarly, a prospective buyer with a C1 licence may wish to own a particular vehicle rated at 3,500kg or lower and would like the additional payload offered by a higher GVW.

Uprating and Downrating is a common exercise in The UK and Europe and is explained in the following link http://www.svtech.co.uk/vehicles/motorhomes/

Anyone contemplating a need to change the GVW of their motorhome should first contact a specialist company like SV Tech and also their local VTN testing centre. The test centre will require a completed RSA MODIFICATIONS REPORT which can be found on pages 149, 150 & 151 of the LGV Testers Manual or pages 209, 210 & 211 of the HGV Testers Manual. Both manuals can be downloaded from the RSA website by clicking on the following link https://www.cvrt.ie/en/About-CVRT/Pages/New-CVR-Testing-Manuals.aspx

Following acceptance of the new GVW, it will be entered against the vehicle's details on the RSA's CoVIS (Commercial Vehicle Information System). While a motor caravan IS NOT a commercial vehicle the RSA continues to treat them as such in most of its procedures and processes.

Currently  there is no procedure in place where changes to vehicle details on the RSA's CoVIS system automatically updates the NVDF (Nation Vehicle & Driver File) and triggers the issue of an amended RF101. A vehicle owner, therefore, will have to pursue a replacement document showing the new (correct) GVW separately with The Driver and Vehicle Computer Services Division in The Department of Transport at Shannon Co. Clare 

Notwithstanding all the above, requests for a change in GVW of motor caravans is a relatively new phenomenon here in Ireland and those of us at Motorcaravanning Ireland are unaware of any published procedures for its administration. 

Going over 3,500kg GVW, even if you have a C1 Licence, may not be the best solution if short of pay-load.

Vehicles over 3,500kg GVW suffer from higher toll rates and/or access restrictions to low emission zones in many countries.

Here in Ireland, such vehicles are also tested on the Heavy Goods Vehicle lane at VTN test centres while those not over the magic number are tested on the Light Goods Vehicle test lane.

Current information from National Driver Licence Service states the following in relation to a Category B Licence:

Vehicles (other than motorcycles, mopeds, work vehicles or land tractors) having a MAM1 not exceeding 3,500 kg, designed and constructed for the carriage of no more than eight passengers in addition to the driver.

The vehicle may tow a trailer (a) where the MAM of the trailer is not greater than 750 kg or (b) where the MAM of the trailer exceeds 750kg the combined MAM of the towing vehicle and the trailer is not greater than 3,500 kg.

Reading the above in conjunction with (a) it is indicated that a motorhome not exceeding 3,500kg GVW may tow a trailer with a MAM not greater than 750kg.

However, it is indicated in (b) that if the trailer exceeds 750kg the combined weight can not be greater than 3,500kg.

See the following link for full information http://www.ndls.ie/en/Driving-Licence/driving-licence-categories.html

It would, therefore, appear to be perfectly legal to tow one of these http://www.spaceextender.com/Medien/Videos/Fahrten_Zusammenschnitt.html or one of these https://www.youtube.com/watch?v=WJgUZyXQh74 to increase overall carrying capacity and at the same time avoid the drawbacks associated with vehicles over the 3,500kg GVW mark.

Such units perform the function of a trailer, but without the instability sometimes associated with one. Also, the challenges encountered when reversing with a traditional type of trailer attached do not exist.