I've been getting a serious vibration at around 60mph with my Sonic. I'm running 16" Continental Soft winter tires, and we've had an extremely warm January here in South Central Alaska. I stopped at a tire shop, thinking I had lost a wheel weight, and they found built up dirt/mud from sand put on our highways was the culprit. They cleaned them up, checked balance (within 1/2 oz) and charged me 20 bucks. Next time, I'll clean my own wheels!
