Check your limited warranty manual. They have a Pro-Rate Chart that coverage mileage. You could get a discount on new tires but it may include the same tire. If you get tires through GM, they will cover labor/mount and balance under your bumper-to-bumper warranty which should be 3 year/36,000 miles.
My 2013 came with Firestone Transforce that only gave me 27,000 miles. Replaced them with Cooper HT3 that gave me 25,000 when I traded and they were soon to need replacement. All 17" tires.
I maintained pressures as listed on the door jam and frequent rotation and were worn evenly. I tow 10,000# about 30% of the time. I have never gotten the mileage tires are supposed to get. That has also included BFG Radial T/A's and Bridgestone.
Tire dealers never offered to prorate tires and I never pursued a warranty.