I have ~16,000 miles on my 20s, the wear is down to 5.5/32 on front set and 7/32 on rear set. I did alignment once (it wasnt much off), and the wear is pretty much even.

I do feel worse handling lately (more "loose" side to side), as they are wearing down. Will try next the Bridgestones, they have slightly better wear indicator.

Wear rate depends on your driving habits, road surfaces and air temperature. I've heard that down in south states they wear out much faster than in the North, as high temperatures keep rubber much softer and easier to "peel off"

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His : 2013 X5 3.5d Deep Sea Blue/Black/Aluminum with ALL packages, 20" 214"s, running boards, Adaptive Drive, Spare Tire, BMW Apps
On Order : 2016 X3 3.5 MSport Silver/Mocha with DHP, CW, Prem, Tech, DA, Lighting

Hers : 2015 328xi MSport Silver/Red

Prior:
2008 X5 4.8
2011 X5 3.5d
2010 335 xDrive
2013 335 xDrive