Never mind, I just found this:
http://http://www.chevrolet.com/owners/warranty/
What's covered:
Tire Coverage
The tires supplied with your vehicle are covered by General Motors against defects in material or workmanship under the Bumper-to-Bumper Limited Warranty coverage. Wear-out is not considered a defect, and it may occur before the vehicle warranty expires. In this case, the owner is responsible to purchase replacement tires or seek coverage solely from the tire manufacturer. For vehicles within the Bumper-to-Bumper Limited Warranty coverage, defective tires will be replaced on a prorated adjustment basis according to the following mileage-based schedule:
Mileage Replacement Percentage Covered by GM
0-12,000 100%
12,001-36,000 Sliding scale starting at 67% at 12,001, proportionately falling (1.96%/1,000 miles) to 20% at 36,000 miles
36,001-50,000 20% (Buick and Cadillac Only)
36,001+ 0% (Chevrolet and GMC Only)
50,001+ 0% (Buick and Cadillac Only)
When a tire is removed from service due to a covered warranty condition under a tire manufacturer's limited warranty program, you may be eligible for a tire replacement or a comparable new tire on a prorated basis. The tire manufacturer's limited warranty program, which can be obtained by calling or visiting the tire manufacturer's Web site or any authorized dealer, is in lieu of all other remedies or warranties, expressed or implied, arising by law or otherwise, including fitness for a particular purpose or merchantability. The tire manufacturers expressly disclaim liability for indirect, special, incidental, or consequential damages, lost profit, loss of business, loss of goodwill, loss of reputation, punitive or any other damage, cost, or loss of any kind.*
What's Not Covered:
Tire and Wheel Damage or Wear
Normal tire wear or wear-out is not covered. Tire wear is influenced by many variables such as road conditions, driving styles, vehicle weight, and tire construction. Uniform tire wear is a normal condition and is not considered a defect.
Road hazard damage such as punctures, cuts, snags, and breaks resulting from pothole impact, curb impact, or from other objects and tire wear due to misalignment beyond the maintenance period is not covered. Also, damage from improper inflation, overloading, spinning (as when stuck in mud or snow), tire chains, racing, improper mounting or dismounting, misuse, negligence, alteration, improper repair, accident, collision, fire, vandalism, or misapplication is not covered. Damage to wheels or tire sidewalls caused by automatic car washes or cleaning agents is not covered.