"Crazy George" wrote in message
...
John:

Before I answer the questions you asked (I notice most correspondents
answered a lot of questions you didn't ask), I want to point out a few
things. Ever think about how many tires wear out every year? You know,
1/2" or more of rubber worn off millions of tires? Cubic yards of rubber?
Where does it all go? Piles of ground rubber along the roads? Well, some
of it remains stuck to the surface of the roadway. Look at any cement
roadway for confirmation. New, nice white or light gray. Old, dark gray
to
black. Now, in spite of EPA, go out and press the leads of an ohmmeter to
the tread of your tires. Not the sidewalls, which may be a different mix,
and usually don't contribute anyway, but to the tread itself. Slightly
conductive, unless they are an unusual brand. So, as you and all the
other
vehicles travel on that fresh, non conductive asphalt, day by day you make
it more and more conductive. So the current which creates the noise, and
is
driven by voltage from triboelectric and other effects, is markedly
different when traveling on a conductive surface than it is on a
non-conductive surface.

So, in the order you asked:
No, you didn't imagine it.
You have noise on old asphalt because it tends to be not a good insulator,
and current flows, creating noise.
Fresh asphalt is much less conductive, so less noise generating current
flows.

--
Crazy George


Well, okay then. That's what I get for posing the question--now I'm
obligated to go measure my tires with an Ohmmeter (when nobody is looking).

I think there were a couple of other posts hinting at this. Sounds like a
winner.

Thanks, Crazy. Er, thanks, George.

John