My philosophy had been to expect solid performance from car tires for three years and after that, they begin to get hard and sidewalls begin to crack. Most of this is based on a car that remains outside most of the life of the tires. If parked in a garage, then maybe stretch to 4 years.
In the past few years my tires dealer has been pushing literature that 6 years a tire is dead. They would not fill my spare with air because of liability of the deterioration of the rubber and the pressure my blow the spare tire. It was a compact spare and 65 PSI. Most regular tires in the 30-40 PSI should be safely inflated. They said that it would probably be safe but it tis the company policy.
I also found back 10 years of so, that all tires have a date manufactured on the sidewall. Some are a code, and some are the week and year of the manufacture.
Since I ride a large Motorcycle and depend on the tires more than a cars, it's critical for the rubber to hold when you only have two tires and use more of the tire. (Leaning into corners, etc.) After three years the tires start to get cracked on the sidewall and have to be replaced in my book.
I believe that the main line (Michelin/Bridgestone/BFG/Yokohama) have a minimum quality to the rubber mix they use on premium tires. They charge more for their tires for some reason, more than advertising budget. Their warranties are better than the lower grades. I worked in a tires manufacturing store that make custom tires and there are different grades / qualities of rubber.
I buy tires that I expect the 3 year miles to be below the warranty. About 30% over.
I drive 45/k in three years, I look for 60Warranty.
Price is important, but not #1. I had better tires that got hard as they wore down and at 4/32 they really just got louder and harder. Tires started at 7/32.
They were done for my purposes and I did get a prorated refund of a few dollars.
I have had tires on a older truck and didn't put many miles on. the tires still had 4/32 but were 7 years old and that had no refund when I went back to the tire store and they said they are out of warranty at 6 years. No matter the miles or remaining tread.
Do your research and think as you buy.