Thrum under feet with strange humming in 2003 PT Cruiser

vibration
noises
#1

Hi. Bought a 2003 PT Cruiser in February with something like 68,000 miles. Have put on about 20,000 miles since then because we live in Wisconsin, and have to drive about an hour to get anywhere. The past month or two, I’ve noticed a kind of a thrum under my feet and hear a new, low humming noise on straightaways. Noise isn’t in the engine, because when I rev it, the noise isn’t there. Seems to be achieve its most fervent humming with very slight vibration around 40 mph and maintains it at higher speeds. Car runs well, no obvious wear on tires, husband did front brakes (with new rotors?) maybe a couple of months ago but I’m not sure if sound coincided with the work, so I can’t blame him. Interstingly, when I’m turning right on curves, the sound and vibration seems to lessen or let up, but not when I turn left. Whatever it is isn’t bad right now, but every since I was a little girl, I’ve had an innate “car sense” and can pick up on things going wrong with relative ease. I hear cars–they speak to me. But, I’m generally ignorant of what exactly might be causing the problems. I’m just a car-hearer, not a car-fixer. Is this a possible wheel bearing, CV-joint, badly balanced wheel, or what problem? Like to have it taken care of by my husband before the first deep freeze. Usually, we’re both out under a tarp in January trying to replace things like bad break lines, timing chains, belts, gears, head gaskets, etc. It would be nice to do it while it’s between 40-32 degrees!

#2

I would suspect either a wheel bearing or perhaps a bad tire.

#3

I would have the wheel balance and alignment checked, and the tires carefully inspected, before doing anything else.

How many miles on the tires?