How long are tires good?

4/32 on steers and 2/32 on drives.

If they’re less than 8 years old and don’t exhibit signs of dry rot they might be ok to use. Something that doesn’t get discussed a lot is heat cycles on tires. Much like hardening steel the more times a tire gets really hot and then cools down completely the more age it puts into a tire. A tire that runs a constant temp range will last a lot longer. Tires that have gotten hot due to constantly being under inflated suffer a lot more.

The big question is how were they stored? We’re they getting the sun on them in Death Valley, or shaded between trailers in a temperate climate?

New tires can be some of the cheapest insurance.