What many don't realize (myself included until a few years back) is that tires can "age out" and still look like new or have decent tread left.
There is a date of manufacture stamped right on the tire. It's a 4 digit number, the first two numbers are the week of manufacture and the second two are the year. I had a 10 year old snow tire explode in our basement while in storage. It looked almost new (until it blew up!). Where I now volunteer, all tires for the trucks are retired after 6 years no matter how "good" its tread condition. This is the rule I now follow, after 6 years, the tire is replaced. Here's a good bit of info if interested:
https://www.edmunds.com/car-care/how-old-and-dangerous-are-your-tires.html
Dave