Vented rear discs - wear limit

[Ste]

There will be a disc minimum thickness, like all other vehicles. I don't know if Vauxhall / Opel publish it though.

Maybe a chat with your local service department may furnish you with the answer. And I totally agree, a micrometer is the only way to measure it, and in several places and take an average and compare to 'published' minimum spec. It's the only way to define when to change them.

[bibu16v]

I know it's old, but as far as nobody got the right answer, here it is:
1. rear discs, internally vented, diameter 292mm, thickness(standard) 20mm, minimum (admitted) thickness 18mm;
2. rear discs, not vented, diameter 278mm, thickness(standard) 12mm, minimum (admitted) thickness 10mm.

[Big Dave]

Sounds just like most discs then. Once the original thickness has reduced by 2mm, advise replacing.

[Dog_Book]

Be good going if the brakes lasted around 14 years anyway

[northpole]

One of the reasons why people get aftermarket upgraded disks... usually they are harder thus less ware in the same time span. but the real difference is in the pads compound... I haven't gone for upgraded disks on the 2.0 dti because the complete brake setup is more than capable of their job and just swapping the pads have made them work better. I did however 2 years ago change all the disks and pads and they are still well within the limits... but if I have to change them again I'll be getting the 314/292 bigger brake setup with Zimmerman disks and Brembo sport pads.... that is if I don't get rid of the car (need more boot space)