We haven't yet purchased our TT but will be in the next few years , right now it's all about the research . There seems to be lots of discussions regarding folks changing out tires and/or axles and/or...
Once you buy an RV you will not need another hobby.
Yes over 12 years I have replaced springs(sagging causing alingnment issues), suspension(worn and was replacing springs), upgraded tires(blow out, lost tread), new wheels(pin hole in the steel), and soon to install disk brakes :B Axles themselves are still original(knocks on wood) and frame is also holding fine.
And that is just suspension. But again that is over time well spent enjoying the trailer.