When you have the rack replaced, the vehicle should be aligned. The tie rods are removed and need to be properly adjusted for alignment.
As far as the humming, first confirm the tires are worn evenly and not cupped or chopped. If they are good, do this. When you hear the humming, (in a safe area) turn left and then right to see if the noise changes pitch. If it does, then there is a good chance it is a bearing. A wheel bearing can make noise and not have any play. I've seen it many times.
Take a look through this link and see if any of the tire wear pics mirror what you see on your vehicle.
Let me know. Also, if the noise changes when turning, let me know which direction you turn to lessen the sound.
Let me know if you have other questions.
Saturday, September 12th, 2020 AT 6:49 PM