I have noticed that Ford is recommending that tires be replaced after six years, regardless of the remaining tread. Apparently, they have determined that the tire's internal components are subject to failure after 6 years and the tires are no longer safe. Ford also says to discard the spare, even if it has never been used.
This article was in the Wall Street Journal, 5/31/05.
Chrysler has apparently had this recommendation for some time; European autos also carry this. GM is not recommending a tire change after a specified period at this time.
My Michelin XC LT4 tires have some very small sidewall cracks. The tires are about 5 years old now. The tire date code on the sidewall says 12001, meaning it was made the 12th week of 2001.
Just wondering if I should change them now, or wait awhile. I still have some tread after 48000 miles. Summers are hot in Texas.