i just bought the car last month. the tires are new, well 4,000 miles on them. checked the air pressure and that was fine. it does it at high and low speeds and the noise stays the same and when i hit bumps it's pretty much the same. now, it's not a really loud noise (more like a muffled thumping). i can feel it, when i have my foot against the floor. it doesn't get worst or better when i brake. the belt look like it's in great shape.