Two things that have arisen from this thread,
Rory White stated
“Ok that's fine, its just some Mazda 6 2.2 litre models have maximum towing limit of 1400kg, meaning your new 1560kg caravan would be an illegal match - unfortunately you have to go by the maximum weights and can't deduct payloads etc.”
Not quite true – It is perfectly legal for a car to tow any trailer provided the actual weight of the trailer (not the MTPLM) is within the tow vehicles limit.
So for example a car transport trailer may have an MTPLM of 2500Kg, but its MIRO is only 500Kg. It is perfectly legal to tow the trailer behind a car with 1000Kg towing limit when empty or part loaded so long as its actual weight does not exceed 1000Kg.
Drivers licence restrictions may make driving such a combination illegal.
Mucky pup added
“The only thing i have found is that the rear suspension is very soft so i fitted a pair of grayson spring assisters to stiffen it up a bit, the ride is a bit harder when not towing but it's a lot more stable with the van on tow.”
It is important to understand the car manufacture designs their car to handle all the loads within its specifications including the trailer masses and its nose load, so spring assistance is never necessary. If an outfit is found to be ‘bottoming’ or not able to handle the nose weight of the caravan/trailer, then the cause needs to be investigated.
It will come down to one or a combination of three things:-
1. The trailer is over loaded or incorrectly trimmed producing an excessive nose load.
2. the cars suspension is worn or broken,
3. the outfit is being driven in an inappropriate manner or over terrain outside the vehicles specification
None OEM or after market spring assisters are never necessary, and should not be used to correct a fundamental fault with the car, trailer or driver. They do not increase any load capacities. They modify the cars characteristics and only serve to satisfy a cosmetic aspiration. If they are fitted as a none standard item they should be reported to you vehicle insures as a modification.