I have seen enough damage to MH's, 5'ers, TT's, trailer's, auto's due to tire failures to wonder why people mess with marginal tires. Unlike a bottle of wine, tires do not improve with age. I have to wonder how many people pay to have the tires removed from their rims and inspected inside, that is the only inspection that is worth a dam and even that visual inspection is suspect. I have yet to meet anyone with X ray vision. As far as Michelin's claim that their tires are good for 10 years with inspections, what do they care it's a sales tool, they won't warranty a tire that blows in 2, as it is always customer abuse to them. In the long run it is a fools bet to mess with tires.
Recently, a friend had a blowout on a rear tire on his MH, a 7 y.o Mich, which had been recently inspected and was told they were still good to go, $4100 later he's on the road again. One new tire and rim and body damage repaired, still driving on the other 5 tires. I walked away shaking my head and wishing him luck. So much for inspections.
Have a nice day.