Tires: Dry Rot, toyota avalon, bf goodrich

Question
I have Michelin Harmony Tires that were purchased 11-24-2004 at 79,000 miles (205 65 15) for a Toyota Avalon.  The Avalon now has 127,000 miles and the tires still have good tread left, however my Toyota Dealer advised me that the Tire is cracking between the treads.  They ride quiet, but I feel they are not safe for my family to ride on.  I wanted to know what warranty Michelin honors and if there is a good resource to contact Michelin regarding this.  I do check my tire pressure weekly(32 lbs. as per manufacture recommendations) and rotate every oil change.  I change oil every 3-5,000 miles. I have been previously using BF Goodrich Advantage series on Camry's and getting 105,000 to 110,000 miles, at less cost.  Also is there anything that helps preserve tires from dryrotting( I live in Delaware)???

Answer
Michelin is the best tire out there and BFG is ok also.

The Michelin Harmony is the only tire made by Michelin I do not recommend.  ( Problems ).

Go to a Michelin dealer or the place you bought them and find out about the warranty.

There is nothing to put on a tire to prevent.  If you put something on, it will cause this over time.

John