Q: Humming sound while accelerating and decelerating. 2012 Kia Optima

Hi there - noises which get louder with increased road speed can be come from tires, or from worn wheel bearings. If there is any vibration felt through the steering wheel, or noises which increase when turning left or right - these symptoms can be helpful in isolating the problem as well. The outside wheels on turns carry more load - so increased noise on freeway on/off-ramps tells you which side is the problem. For assistance, I recommend a noise inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, and give you an accurate assessment of damage and cost estimate for repairs.