A few weeks ago my '99 SL2 started making a disturbing noise. When I am
braking to stop, I'm getting a noise that from what I can tell seems to
be coming from the front driver's side wheel or tire. It is difficult
for me to describe the sound in words: I'd like to say it's sort of a
low-pitched clicking noise, but I could also say it's sort of a "whup
whup" flapping (or rattling?) noise. (It really does sound like a click
or rattle, except those words usually describe high-pitched noises, and
this is fairly low-pitched.) The noise is definitely correlated with
the spinning of the wheel - as the car slows down the noise slows down
as well, and stops once the tires have stopped. No noticeable
shuddering or vibration associated with it.

My car was just inspected this morning and passed without needing any
work, so whatever the problem is, it wasn't something found during a VA
state inspection. I tested the shocks and they behaved normally. My
tires were rotated 3,000 miles ago and the wheels were balanced with
the purchase of new tires 15,000 miles ago. Car drives straight as an
arrow, so alignment doesn't seem to be an issue. I was inclined to
think perhaps the tire was cupping anyway, but when I examined the tire
it didn't look that way (I might have just not known what I was looking
at?). My other thought was that it might be a worn brake rotor. How
long might one expect brake rotors to hold up? I purchased the car at
about 95,000 miles and it is now at 125,000. I am unaware of any
maintenance done prior to 95,000 miles, but have not had any brake work
done since buying the car.

Any ideas?