I am new and need advice
 

Hello, I am Jennifer. I am on my second IS250 The only complaint I have is the tires wear too fast. I want to know what is the hardest tire I can put on the car. Can I go outside what the Lexus dealer recommends. If so, or not why??? I am trying to not have to go through new tires every 1.5 years/15k miles per yr.