I'm sure its been talked about in the past, but I can't find it. I have Good Year tires on my p/u with only 30k miles and lots of tread left, but they are original tires. The sidewalls are clean no ...
If the vehicle is stored indoors I would easily go 7 years. If not then inspect them. Car tires can last longer than trailer tires. But if your not sure, then replace them. The tread is probably around 50% so they are nearing the end of their useful life anyway.