Most vehicle tires are good for around 30,000 to 50,000 miles before they wear down and need replaced.
Another thing that affects tires life is the age of the tire and as the tire gets older the rubber gets degraded and starts cracking.
Eventually the steel in the tire will separate and start coming out of the tire and then the tire could blow out eventually on the road.
So if your tires are 10 years old or older they should be replaced regardless of tread life or miles on them.
Tires that are old can cause a serious wreck which could be fatal to you, your passengers or someone else on the road.
My Tires typically last 50,000 miles which to me averages around 5 years because I drive around 10,000 miles per year while some other people may drive 20,000 miles per year and need to replace the tires in 2 and 1/2 years.