Rule of thumb from what I've heard is 5-7 years for tires of any type, trailer or car/truck.
"Bridgestone recommends that its Bridgestone or Firestone brand tires be removed from service after ten years regardless of their remaining tread depth. They also recommend periodic inspections by a qualified technician for damage such as punctures, impact damage, signs of improper inflation or overloading, or other conditions resulting from the use or misuse of the tire."
From Discount tire web site: "How Long Do Tires Last?
The average life of a tire is determined by the conditions a tire is exposed to throughout its life - not measured in calendar years. Temperature changes, sun exposure, storage conditions, usage, and maintenance schedules all contribute to the rate at which a tire ages.
It is impossible to determine a tire’s exact life expectancy, because there is no way to account for the level of influence any one of these factors may have on a tire. However, you can defer to the vehicle and tire manufacturers replacement recommendations:
Vehicle manufacturers recommend tire replacement at 6 years.
Tire manufacturers' warranties expire at 6 years.
Tire manufacturers recommend replacement at 10 years, regardless of tread depth.
Discount Tire recommends that you replace your tires after 6 years of age, regardless of tread depth. For your safety, Discount Tire will not service a tire that exceeds 10 years of age."
Of course, Discount tires sells tires.....so ?
I would add, growing up on the farm Dad bought a new 1949 IHC KB5 two ton farm truck which was used until he retired about 1979 and sold it with the original tires - only ran about 20,000 miles. Also had a 57 Ford two ton farm truck, purchased used and sold about 79 - never replaced the tires. Car tires were never replaced until tread was nearly gone growing up and I still don't to this day.
So maybe with all the huge advancements in material, design and tire manufacturing, they just don't last as long as they used to anymore if must be replaced on cars, trucks, etc. in 7-10 years.