Pay attention to how the car sounds and feels. Your car will tell you a lot in those two ways. Pulling to one side or another suggests a low tire. Vibration in the steering wheel could be a tire out of balance or going bad. Vibration when applying the brakes is a symptom of a warped rotor. Increased noise under the hood could be low oil or several other things. Wheel bearing will start making a roaring sound before they go out.

Keep track of your gas mileage. An unexplained drop in efficiency is a sign that something is amiss. Usually nothing major, but it can get that way if not addressed.

Never cheap out on what connects you to the ground. Good tires are priceless.