Uneven tire wear on 2007 Buick LaCrosse

If a tire is wearing on the inside, what causes this.

3 answers
Usually caused by a toe out condition, possibly hit a pot hole or curb can cause this. Usually a alignment will solve this.
Excessive positive Camber is connected with this type of wear also.
Again the wheel alignment needs to be checked first.
Bad springs can cause your tires to wear on the inside. Everybody has been using cheap springs, poor quality control/testing.