Does it happen all the time, or just a new thing? Has the trailer been put up for the winter and it happened on the first trip out? My first guess is that you have bias-ply tires and they have been sitting for a while and have flattened one side, (but not the same connotation as flat spotting). If this is the case they should return to round when they are put into normal seasonal use. Might want to check air pressures too.

Rich

I can stall the sails with the best of 'em!