I just made a 800 mile round trip to Chickamunga. One the way home trailer developed a bad vibration on one side. Checked all four wheels for heat and they were fine. When I got home, I found both tires on one side had a large flat spot. Break tire had a slick spot about 14 inch in center of tire and the front tire had a 8 inch slick spot. Could this have caused the vibration ? Secondly, what would have caused the flat spots ? The trailer is a 2018 Tracker and the tires have appx. 20,000 miles