The best way to tell if you need new brake rotors is by looking at them.
If the brake rotors are glazed over or have cracks or are really thin or are rusting out then you need new brake rotors.
Also if you have any vibration in the steering or hear intermittent screeching sounds or notice blue coloration on the rotors then it's time for new brake rotors.
Ideally brake rotors should be replaced after every 2 brake pad changes but sometimes they may last longer.
The cost to replace a brake rotor ranges from $150.00 to $200.00 for a shop to do the job and if you do it yourself then the cost to replace a brake rotor ranges from $40.00 to $150.00 for the rotor.
You can buy brake rotors online through Ebay and other parts stores cheaper than you can buy them offline.
On a car with all disc brakes there are 4 rotors on the car.
On a car with rear drum brakes there are 2 rotors on the front of the car and 2 brake drums on the back.
Car rotors also known as brake rotors are a metal disc that are attached to the wheel hub of the vehicle.
The brake caliper sits over the brake rotor and when you press the brake pedal the brake pads make contact with the brake rotor and stop the vehicle through friction.
Discs or rotors work by pads that clamp down on the rotor to create friction to slow your vehicle.
The pads indeed wear out first.
The rotor's primary function is to absorb that friction.
The more worn down your rotors are, the less heat they can absorb at one time, which results in longer stopping times.
Brake rotors that have gone bad are usually either warped, cracked or just have gotten thinner as the brake pads wear them down.
Most brake rotors will easily last 100,000 to 200,000 miles and sometimes longer.
If you notice any cracks in the brake rotors or the brake rotors are warped or have gotten thin then you should replace them.
I have had a brake rotor shatter before when I failed to replace a cracked brake rotor so if you see any cracks developing in the brake rotor then replace them.
Brake rotors should be replaced in pairs.
Some people need to replace their brake rotors every 80,000 to 150,000 miles and some people may need to replace the brake rotors after every 4 sets of brake pads.
If you do a lot of towing with your vehicle then you may need to replace your brake rotors much sooner than someone who does no towing or hardly any towing at all.