Hyundai Forum - Hyundai Enthusiast Forums - noisy drivers side suspension

Hey everyone i am a brand new Hyundai Sonata owner and have had american cars my whole life and had a couple of questions about my Sonata. I purchased the car used with 11,00o miles on it about three weeks ago. When i bought it from the dealership i drove it home and the next day checked the air pressure in the tires and they were barely 20 PSI, wow. I immediantely pumped them up to about 30-35 and everything was fine for a couple of days. Then one afternoon i was going over a speed bump going like 10 MPH and heard a squeaking noise or moaning nooise coming from the drivers side tire and suspension. I thought that was odd so took it back in and they said i had the tires overinflated and that the noise may be coming from the plastic hubcaps, and said they adjusted it. Unfortunately it is back again and am getting really upset because i know it isnt right and dont feel like taking it back to them to tell me everything is fine with it. Has anyone else had this problem. IT is an 06 sonata GLS, with plastic hubcaps thanks if anyone has any ideas feel free to write me back, thanks.