axle/tire problems

I have a 27ft Forest River Travel Trailer, less than 2000 miles on tires, only camp local and only had 14 months. The tires on the passenger side have tread worn on the outside edges only, drivers side is cupped. Took it to the dealer, they did a laser alignment and stated rear axle is 1/4" out of line, said I needed new tires because they were not the right ones, they should have not been filled with nitrogen and that I needed an alignment and lift kit installed. Everything is from the factory, I have not done any thing to it. Does this sound normal or a factory problem. I can have all the work done and "it may" correct the problem for just under $1300.00. I feel like I'm being taken...Any thoughts