I've got 15k on my DWS (driven at high speed on the highway, and darting in/out of traffic in the city) and I'm still at 8/32R nd 8.5/32F. My only suspension mods are Powerflex bushings (including rear subframe) and Dinan camber plates.

I do carry ~100lbs of tools/computers/measuring equipment around almost all the time.

To the op: what are your tire pressures? Anything less than 32psi on these is too low.

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2011 Sapphire Black X5D
Burger Tuning JBD
Lux H8 V4 Angel Eye LEDs