@Colin Parkstone wrote:
If I was you i would have a look at the suspension units and see if they are working properly.
How true, the suspension units of my road base had to be replaced after less then two years of use. (Actually they are combined hub/suspension units, you can’t exchange the suspension only). My local trailer specialist deemed them too light for my purpose and mounted a stronger suspension set that can cope with the weight of the boat including all my gear and what not. The original suspension was (theoretically) just strong enough for the empty boat. One of the symptoms was a negative camber angle and consequently an uneven tread wear.
I am not saying that all combi-trailers suffer from too light suspension units but if mine had this problem there must be more out there.