Contact member Fasteagle. He I believe he works for Power King maker of Tow Max tires and he should be help you with your problem. I think he regularly gets free replacements so he should be able help a fellow member of RV.net. Even though it is most likely your fault for not maintaining them correctly, he should be able to help make your case with Power King. Tow Max recently added a Nylon cap similar to what Goodyear added to the Goodyear Marathon years ago so that they are more reliable, so replacements should last twice as long. Good luck!
Chris