60K on my tires.
Michelin Primacy MXV4s. 205/65R15s on a W124 E320 sedan.
~50% tread still left (6/32). Barely, but more than 38% (5/32nds.)
Still no complaints. Low noise, excellent rolling resistance (averaging 23.5mpg for a car that is epa rated 18/ 24/ 20.) and decent in wet weather of which we don't get much in Southern California.
Some weather checking on the sidewalls (my car lives outside at home and at work.) and greying of the rubber. But both are normal.