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

However more ofthen 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 posess a category C1 licence (or higher).

As motorhomes find their way onto the used market their exixting 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.

Simirarly 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 excercise in The UK and Europe, and is explained in the following link http://www.svtech.co.uk/motorhomes.html .

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 center who will require a completed RSA MODIFICATIONS REPORT TEMPLATE (LCV) see Section 60 page 97 http://www.rsa.ie/Documents/Vehicle%20Testing/CVR/LCV_Manual_final_version.pdf for vehicles not exceeding 3,500kg GVW. For vehicles over 3,500kg GVW a completed RSA MODIFICATIONS REPORT TEMPLATE (HCV) see Section 71 page 147 http://www.rsa.ie/Documents/Vehicle%20Testing/CVR/HCV_Manual_final_version.pdf is required.

Following acceptance of the new GVW it will be entered against the vehicles details on the NVDF (Nation Vehicle & Driver File) by the VTN center. Unfortunately, the ammendment does not currently trigger the issue of an ammended RF101 and the vehicle owner will have to persue a replacement document showing the new (correct) GVW seperately 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 motorcaravans is a relatively new phenomenon here in Ireland and those of us at Motorcaravanning Ireland are unaware of any published procedures for its administration. 

http://www.rsa.ie/Documents/Vehicle%20Testing/CVR/LCV_Manual_final_version.pdf

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

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

Here in Ireland such vehicles are also tested on the Heavy Goods Vehicle lane at VTN test centers 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 breater 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 asspciated with one. Also, the challenges encountered when reversing with a tradition type of trailer attached do not exist.