How many miles do tires last on a tractor trailer?

If if if.... If you don't curb them, run over stuff, maintain proper air pressure, and keep them balanced I have been able to get 150,000 miles from a good set. I have heard unconfirmed numbers of some guys getting above 200,000. However under normal conditions where air pressure is never checked curbs are hit and tires are never balanced you'll get between 50k and 75k.