Q: Loud humming noise under drivers side feet area. on 2004 Chrysler PT Cruiser

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Huge humming noise especially when I drive at 30 - 35 miles here per hour. It is not the wheel bearings - had checked. I am thinking is in transmission. I feel under my feet as drive. At freeway speeds... 60-70 drives fine - no steering problems. Is there a bearing in the transmission on this car. I do not hear the hum when start up (at least loudly) but can when driving slowly as in my apt. complex around 10 miles to go to car port after freeway speeds here too. Sounds like a plane overhead at times - that loud. Or could this be a differential going? What is cost to repair? Car has 130,000 miles on it. Thank you for any advise. I have a limited income and so am not sure how to proceed. Am disabled.
(1) Answer
It still sounds like the front wheel bearings to me, however, Before you panic, have your tires rotated front to rear in a cross pattern, RF to RR, LF to LR, RR to LF, LR to RF. If you have directional tires, disregard the cross rotation.