When you have to push very hard down on the break pedal to get the car to stop, then your really in need of new break pads. When your car doesn't want to stop when you put on the breaks than you know you need new break pads. I could tell because it seemed like my car was kind of skidding to a stop but really I needed break pad's way before that and just got lucky that nothing really bad happened. Some car's have what they call and "idiot" light that a light on your dash board lights up that says "breaks" but I am not sure if that just tells you you need more break fluid or if it tells you when your breaks are shot. I hope this answer helped you in some way.

A lot of modern brake pads have squealer strips in them that cause the brakes to make that screeching sound when the pads are low and need to be replaced.

Also, since the brake pads do physically get shorter as they wear, you will find that you have to press your brake pedal a bit further as they gradually wear out.

Another way is to buy some brake pads, look at them, take off your tire and look at the pads themselves. If they look worn or lopsided, then consider replacing them.

Your mechanic has years of experience and has probably replaced thousands of brake pads. You can't buy that kind of experience, so taking it to your mechanic if you don't feel comfortable replacing them yourself, makes a lot of sense.

If you are having braking issues it could be you need new pads. It could also be something else such as low brake fluid.

With the wheel off, there is usually a 'window' in the caliper (the thing which squeezes against the rotor) that you can look through to determine the thickness of the brake pad. You would have to find out for your specific car at what thickness it is recommended to change them. Also with the wheel off, you can feel the rotor (the round thingy the caliper squeezes). It should be pretty smooth. Feeling the rotor by hand can't replace inspection by a shop, it is good enough to find serious wear to the rotor. Large grooves or uneven wear in the rotor can mean you need new pads or there is some other problem with the brake system.

As others have said, when the brake pads are low, they should squeal, but I wouldn't rely upon that. If you are having braking issues, check them or have them checked.

If you do this inspection yourself, please make sure you properly lift and secure the vehicle. Here is a pretty good Youtube video you might want to check out. http://www.youtube.com/watch?v=1XFgRXBaDmU&feature =related

There are a few different ways to tell
You can visibly look, they should be 3/8" thick and also check the rotor for grooves. You also can hear them grinding, and on some vehicles they have wear sensors which will omit a high pitch sound.

The brake pad consists of two materials , a steel backing plate and the friction material ,
glued or riveted in place , if the brake pad material that touches the rotor is the thickness
of a coin , a dime or penny , its time.

When you push your break but your can't get break as you wish and when break pads was new. If you having problem and can't get wish-able break you need to change this.

What he is looking at is the ware tab... there is one at the top and one at the bottom of the brake pad. and what he is checking for is the space between the rotor and it this lets him know when your brakes are ready to be replaced...

next time your in a auto parts store ask to see a pare of your pads.. so you can see what the ware tab looks like

i hope this helped

You can tell that your brake pads need replacing when they squeal every time you touch the brake pedal.

As correctly stated earlier, the brake pads are made up of steel baking plate and the friction material. While many vehicles are fitted wear indicators of some sort, generally the metal "squeaker" tabs or electronic wear sensors, even if fitted and working properly, these are a poor indicator of brake pad wear as there is generally only one sensors fitted to the front and one sensor fitted to the rear, there are only two sensors and eight brake pads.

What you are seeing the technician do is a visual inspection of the remaining brake pad friction material. The metal backing does not wear unless the vehicle is driven to the point where there is absolutly no friction material left and the steel backing of the pad contacts the rotor. When this happens there is no boubt and the driver becomes instantly aware of the need for replacement. Unfortunatly, should this occur, it becomes not only neccessary to replace the brake pads but, also the effected rotor(s), a much more costly situation.

Visual inspection of brake pad wear can be greatly aided with the use of a flashlight and a telescoping mirror. These will help you get the line-of-sight needed as it can be difficult to see the pads, especially the inner pad while fitted in the calipers and the wheels on the vehicle.