How to measure brake pads?

Could someone point out to me where am I exactly measuring the pad thickness from when I check to see if my pads need replacement? I've done a lot of searching and I know that new pads are 10mm and should be replaced at 2.5-2mm of thickness, but is this measured from the rotors to the beginning of the brake pad back plate? Also. the red metal rods seem pretty close to the rotors so I can't see wearing out my pads until the 2mm mark. Pictures and points of reference would be very helpful thanks. Above is a picture from the "how to" article.

I replace mine when the pad brake compound is the same thickness as the same as the pad backing plate.

clee: Your measurement points for pad thickness are correct; from the face of the pad (the part that's getting worn at the rotor) to the backing plate.

That seems overly conservative...unless it's right before a track weekend. Even then, I'd bring a new set and change when appropriate. ed

The thinner the pad, the greater the heat transfer to the caliper and fluid. You have a higher probability of brake fluid vaporization and resulting brake fad with thinner pads. Whether this actually occurs depends on lots of things, like pad/fluid type and how aggressively you are braking. I agree with Sleepless: pad thickness equal to backing plate is a good rule of thumb. Of course, I've also squeezed out a few dozen more laps if I didn't have a spare set handy... Some PCA's DE's will not allow you to pass tech with pads less than 50% of original thickness.

The rods do not get any closer to the rotors. They are fixed to the caliper.

Are your brake pad wear sensors in place? If so, then obviously they will let you know when Porsche thinks it's time to replace them. If you want to replace your pads before you trigger the warning light (and have to replace one or more of the sensors as well), then you can also judge by how close the wear is to the sensor hole.