Almost 3 years on the OEM DURO Bias before separation. I recommend 2 years max on cheep OEM tires.
Then just over 3 years on Denman Express radials before a tread came off. These were supposed to be 'good' but the company soon went BK so probably quality was dropping in the end.
Now almost 4 years on MAXXIS and plan to go 6... knocks on wood.
Recently had a cracked steel wheel (air leak) so was able to justify some higher rated (and better looking) aluminum wheels.