2009 BMW X6 Tires Problems

I OWN A BMWX6 2009 AND UNDER 30,000 MILES I HAVE TO CHANGE TIRES UNDER NORMAL DRIVING CONDITIONS. THE OWNER MANUAL INDICATED THAT TIRES NEEDS REPLACEMENT AFTER 6 YEARS THE MOST. THE TIRES THREADS UNDER 30,000 ARE UNDER SPEC. AND RECOMMENDED TO REPLACE THEM BY BMW SERVICE CENTER. I REPLACE THEM AND I FOUND OUT THAT MICHELIN IS NOT GIVEN A WARRANTY FOR TIRES INSTALLED ON BMWX6 2009 EVEN THAT ON THE OWNER MANUAL IS A STATEMENT THAT THE TIRES ARE WARRANTED BY THEIR MANUFACTURER. WHY A BRAND NEW CAR IS SOLD WITH TIRES WHICH ARE NOT UNDER WARRANTY? NOT TAKING A CHANCE TO HAVE AN ACCIDENT I REPLACE ALL 4 TIRES AT MY COST OF OVER $1700 AND BMW IS NOT TAKING ANY RESPONSIBILITY THAT THE TIRES ARE WEARING OUT TOO SOON AND TO INFORM ALL THE OWNERS OF A POTENTIAL DANGER DRIVING THE CAR WITH TIRES WHICH ARE...