I have always wanted a set of 3/8″ red line tires. I purchased Coker manufactured Red Line American Classic tires, same size and when replaced had bad vibration after standard balancing, Coker tire MFG very helpful and set me up with local dealer for Forced Balancing. this is best balancing possible and checks rims as well. One tire out of spec and had to be replaced but still vibration that car never had before changing the tires. Vibration not in seat but felt in steering as if oval wheel. A call Back to Coker tire and they were helpful by sending me 4 more tires that were pre force balanced at the factory between 11-14 lbs road force. Up to 35 # is acceptable range so these readings were great. Had them re installed and re force balanced with excellent readings. Car still has a vibration like and oval wheel but better at high speeds. No bent rims as force balance machine checks that so what can be the problem? Car brakes fine no shutter or vibration and all wheels are cool so that stumps me. Please help as this is a frustrating mystery and who do I go to next?
If the vibration is felt in the steering wheel, rotating the fronts to the back would be a quick check. If the vibration does not follow the wheels to the back then you know it isn’t in the wheels. So you are left with the hub bearings, rotors and steering components. Most common would be the rotors, even if the typical brake pedal pulsation is not felt.