How do I inspect 2005 jeep grand cherokee brake pads?

I have a 2005 Jeep Grand Cherokee 5.7L. It has 57k miles with 90% of that highway driving. When should I change my brake pads and how can I inspect them?|||Most brake shops do free inspections|||jack it up take off the wheel look at the brake pads if they are about the same or close to the medal backing they are glue to they gone.... most start out new with like a half inch of pad and when it gets to like a 1/4 inch they gone much pass this point you run a chance of them grinding the rotors and when that happens its costly i alway just look at how thick it is compare to the backing that there come on and best to check the right side for they wear faster and the back side of the rotor is most always les sthan the front you can really see the back so if its down a round a 1/4 its time|||remove the pads and look at them if the are about 1/2 in or less chamnge them.