I have had my NX for nearly a year and no issues as yet.
Certainly if I am in the car stopped, it remains in ready mode. I don't bother with ready mode when washing etc. and haven't had a problem.
I have left the car unused for over 3 weeks and again, no problems.
I don't know about the tyres. It would be worth asking your dealer if they can get tyres easily.
Good luck 😀