You'll need to use a gauge like this:
http://www.northerntool.com/shop/too...3622_200343622
Or take them to a brake shop and have them measured.
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2015 BMW M4— Mineral White on Sakhir Orange/Black DCT
2012 BMW S1000RR — Racing Red/Alpine White - Sold
2009 BMW M3 Coupe — Alpine White on Fox Red, DCT - Sold
2003 BMW M3 — Carbon Black on Black, 6MT - Sold
1995 BMW M3 Coupe — Cosmos Black on Black - Sold