I have 37000 as of today on my stock Michelin LTX M/S tires. Compared to the still brand new spare of the same tire, I judge they should get me to 65K or better. I have always had excellent luck tread life wise with Michelins, and unless I need a seriously agressive offroad type tire, I don't plan to ever change to any other brand. Although, Michelin does make some excellent offroad tires as well. Just check out Bill Swails Earthroamer truck.
Tom