Myxtreme1

There is a mysterious thunking sound coming from the rear on my Tahoe(seemingly from the wheel/ brake area). At first it seemed to be started by pressing the brakes but now it seems to be doing it no matter what around 15 mph. It maybe doing it more often than that but that is just when we hear it. I even stood outside of it while my wife drove by close and it was very loud. It seems to be with every revolution of the wheel. The truck is still under warranty and I need to make sure they are going to get this mess fixed. There also seems to be a similar sound coming from the front but I didn't hear that when she drove by. Any help will be very appreciated. Thanks!

P.S. The only thing different is that I upsized the wheels
and it has 40,000 miles, and I have tried to look for help on
the truck forums.