Used tires are never a good idea. They could have a slipped belt or out of round. The brand “starfire” is also sketchy. Always buy tire brands you recognize. Sorry but unless you have it in writing, you now own these tires without any recourse.

Drain and fill will be fine.

I’ve already tried moth balls. I assure you, mice don’t care. They built a nest right next to a pile of moth balls I left in the trunk of my car.