Rubber degrades with age, whatever the tread looks like. Enter your DOT code and find out where yours stand.
Most people judge a tire by how much tread is left. That tells you about grip in the wet — it tells you nothing about the condition of the rubber holding it together.
Rubber hardens and develops fine cracks as it ages, whether the car is driven daily or sits in a garage. A tire with plenty of tread that's twelve years old is not a good tire. This catches people out most often on spare tires, low-mileage classics, and cars bought used where one replacement tire is years older than the rest.
Las Vegas makes it worse. Sustained heat and UV exposure age rubber faster than a temperate climate does. A tire that might see ten years somewhere mild has a harder life sitting on 115°F asphalt.