Take your trailer to a reputable frame and axle shop, and preferably a gov't certified one if you have such a thing. Pay the couple hundred $$ and get a detailed inspection. Do NOT try and resolve this with the dealer. Extended warranties are a waste of $$.
Stating you overloaded your TT or caused it otherwise is a standard Lippert excuse. Problem is, there are no industry standards for RV frame construction and Lippert can do what they want.
Many TTs these days have super cheap, weak frames and sometimes also have manufacturing defects. These are the ones that have I-beams that are made from 3 pieces of mild steel welded together to make what looks like a "regular" I-beam. These flex a lot and can cause serious problems. Extremely unlikely to be a tire or rim issue or an axle that you bent. Weighing the TT at a scale might also help to show you're not overloaded.
We had a previous TT that had one of the above frames and we managed to get it replaced under the basic factory warranty. Day after we owned it from new, I took it to a local independent RV shop looking for some propane fittings & parts for under the TT. The owner crawled underneath and noticed some odd issues with the frame.
Initially we took the TT to the dealer. They sent photos to Lippert who allegedly came back and said "it was within spec."
We then took it to a gov't certified inspection facility (a frame & axle shop) who did a thorough inspection and ended up saying it was the worst frame they'd ever seen and should be condemned. Spring hangers were bent to one side, lower "web" of I-beams were damaged at spring hangers, welding was bad, to name a few issues. We sent a copy of the report to the TT manufacturer and dealer and within days they said they'd replace the entire TT. When we got it, it had a MUCH heavier duty frame. Original frame was 6" tall and new one, 8" and with forged type I-beams. Also came with 12" brakes. In the 7-something years we've had it, not a single frame-related problem. (many other problems tho.)
If you have one of the weak welded frames, they have a LOT of vertical flex. While doing a wiring mod, I found a failed weld in the aluminum framing due to the flex. Also, the entry door would "parallelogram" and once the door flew open on the highway as a result because the latch would get out of alignment while the frame flexed. There could have been other failed welds, dunno.
I hope it all works out in the end for you.