I’ve got a unicorn in the shop (pics later maybe) with 8 year old tires. But they still have 10/32” tread remaining. This resulted in me learning that a scary amount of people haven’t heard of tire ageing. At the very least, inspect and consider replacement at 6 years. NTSB link for funsies.
Tire Aging and Service Life - NTSB
PDFhttps://www.ntsb.gov › news › Documents
If the link doesn’t work, try this one, or search “NTSB tire age”, should be first or one of the first: