Pull the ABS motor fuse and test it again. If it is the ABS or linked brakes it should stop. Replace the fuse after your test to regain the ABS and linked brakes. If you really think it's the tire, it may just be a defective tire. See if you can get it replaced under warranty, or just replace it ifi t bothers you so much that you would spend ~$200 on the off chance it might fix the problem.