Tire Life & Age replace after 5, 7 or 10 years ?

I have read the Michelin guide in great detail. They seem to really know their stuff and was interested in their assessment that RV tires should be changed after 10 years max regardless of mileage. So, depending on how long it took to get from the molds to the MH, the life would be somewhat longer than the date stamp.

OK, this makes sense but I keep hearing reference to 7 year service life, 7 years from date stamp, and even 5 years from date stamp. This seem to contradict Michelin and I guess I'm wondering who's right and what is the source of the other life expectancies. Is the info from companies/researchers as reputable as Michelin or merely Internet opinions.