Tire cupping

[Cadillac Charlie]

Car is an 07 two wheel drive Escalade with 18,000 miles. I rotate and balance about every 7000 miles. At 15,000 miles, left front tire began to cup on inner edge, alignment check showed minor misadjustment, realigned to factory specs and rotated again. 1000 m iles later, LF showing cupping, rechecked alignment, showing very minor misadjust, realign, rotate again. Now at 18,000 miles LF again cupping. Took to dealer, says nothing wrong with front end, alignment OK, must be rotating tires incorrectly; on rearwheel drive must crisscross front tires when moving front to rear. Anyone else haing this problem or can comment?

[mike]

I am having the same problem on the same vehicle...I am getting rid of the Bridgestone tires that come on it for another brand...have been told that is the only fix. The dealer told me he is doing the same thing on his mothers Caddy.