A vehicles tires should last between 50,000 to 80,000 miles or 10 years whichever comes first.
If you drive an average of 12,000 miles per year then you would reach 80,000 miles in around 7 years and by that time the tread will likely be worn down enough to need replaced.
At 7 years old the tires are getting old anyway and I would replace them after that time.
Tires should always be replaced after 10 years because even though the tire might have good tread the tire will have cracks around it such as in the tread area and the sidewall which could cause it to blowout especially at highway speeds.
I get around 50,000 miles out of my tires but some people may get more miles out of them.