I replaced my Michelins 2 years ago on our 2006 at 5 years due to excessive sidewall cracking. jmho, have them inspected by a trusted pro tire shop.
Replaced the Michies with Hankooks. Hankooks still look like the day they were put on after several thousand miles and going on 2 years.
I just don't mess with tires. Years ago had a couple blowouts on 5+ year old tires. No major damage, but learned one thing. I don't mess with extending the age of tires. I get them inspected, and if need replacing, the piggy bank gets robbed.
Personal peace of mind while going down the road = priceless.