In my limited experience with wheel bearings they get louder with age

The noise is getting louder than when previously reported. I still have not had it checked out by a mechanic. I would like to get a better grip on what the problem could be.

I temporarily swapped my rear wheels to my original 17" and drove on local streets and at freeway speeds. The noise still exists. I thought it could be tire noise. I am going to get the 18" tires re-balanced anyway.

I can best describe the sound as this: The howling is a low pitched rhythmic sound that rises in frequency as speed is increased. The howling starts at about 40 mph. The sound does not radically change when driving on asphalt or concrete surfaces. The sound does not appear to change or disappear for different loading conditions (right turns vs left turns). It is pretty loud when driving on the local freeways. The sound appears to be from the driver's side rear. But since my seating position is closest to that corner, I could be misled.

When I had the wheels off, I rotated the axles. I did not feel or see anything unusual (suspension components intact, brake pads have remaining life, axle boots intact, no roughness felt when turning axle- but this is at a low force rate).

I want to be a bit more knowledgeable before I take it in to my local indy.

Thanks.

and if that is happening with your car you may want to consider them as the source. if I remember correctly, there was a little increase in noise in relation to speed.

... then it's probably just a loud tire.
Happy Boxstering
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

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Racecar spelled backwards is Racecar

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"If you wait, all that happens is that you get older"... Mario Andretti

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Might they be Pilot Sports? My car's PSs develop a subtle whumping or droning sound after some time. The amplitude's cycling frequency would increase with vehicle speed. Moving the tires (only) to opposite sides while maintaining direction helped for a while.

but my mechanic switched the wheels and the whomp sound switched to the other side, hence not a bearing problem...more like "cupping" on the tire from uneven wear or taking turns too aggressively. As Pedro stated..."Occam's Razor." If the sound doesn't switch over, then seriously consider replacing your wheel bearing.

Good luck