Measuring brake disc and pad wear

[james250]

Does anyone know how to easily measure brake disc wear for IS250? does the wheel have to come out to measure the disc? also what about measuring brake pads wear? 

[Farqui]

Take a peek here; 

Are your rotors badly scored/worn and/or rusty?

[johnatg]

You need to take the wheel off and use a micrometer across the thickness of the disc or you can use a couple of nuts either side of the disc and measure across the whole lot with a caliper then subtract the total of the nuts thickness. You can't just use a caliper by itself because you'd be measuring the thickness at the rim and there'll be a lip there if the discs aren't new.

Note that most micrometers are 25mm max opening but you can get bigger ones. Dial caliper gauges are cheaper and have much bigger capacity.

Most of the time you can tell that discs need replacing just by looking at them - general corrugated iron effect is usually more significant than straightforward wear.

You can expect a disc to last for two sets of pads - ie need changing every other set of pads.