This isn't about my cx-5 but I know this forum is full of smart people so I'll ask about my sister's Honda Fit. I noticed her outer part of tires are worn down. I'm assuming she hasn't been on top of adding in air over the years. The car has 35k miles but the outer part of the tire looks bald while center has the ridges. I put a penny in it and the outer groove is definitely showing the full head. I've started to top off her tires each month. is it safe to drive around like this since she does short drives 1-5 mile trips of should the tires get replaced. I'm assuming that if the middle of the tire thread tis still good and if tires are getting filled, its ok to drive like this.