I've got a 98 s70 T5 with almost 150,000 miles on it. A couple hundred miles after I had the tires balanced at an NTB, a periodic "whoomp..whoomp..whoomp" sound started coming from the passenger front tire area. It sounds like something is rubbing and the sound does happen more often the faster the tire is spinning. It was originally intermittent but it is now louder and constantly present. The sound is also louder if the steering wheel is biased a little to the left or right. The brakes work normally, the car handles fine and I haven't detected a drop in mpg.

I had a mechanic look for the problem when I first noticed the sound, but he didn't find anything. I did notice the passenger front tire had two unusually large balancing weights. I took the car back to be checked at a different NTB and they confirmed the tire was improperly balanced. Rebalancing the tire did not eliminate the sound. I asked them to look for the source of the sound but they didn't find anything.

Has anyone else had a similar experience and found a cure, or have some suggestions on what to check next? Thanks.

Sounds like that at this point your tire is out of round. Try changing the tires around to see if that sound goes to another tire. I'd bet about anything that's it.
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon

When I brought the car back in to NTB, I asked them to check for an out of round condition but they said the tire was OK. I should have had them rotate the tires to make sure. Thanks for the suggestion.

Then consider that the wheel bearing assemble may be defective if you haven't replaced that yet. Mine went out at 89k miles. Mine sounded like tire problems, but replacing the bearing assembly solved the problem. Fairly easy to do yourself if you follow the bay 13 instructions.

I checked the Bay 13 info and the symptoms do match. The sound is louder when turning left. FCP groton carries the bearing hub kit for $149. I'll see if my mechanic can confirm this is the problem before ordering the part. Thanks.