Hi Mark

I'll admit I have never actually noticed it but your experience sounds
plausible.

So me thinking in fundamental terms.

- The ground strap not working implies a charge and discharge cycle in
the wheel/axle.
- When you corner the tyre/road, tyre/wheel, wheel/axle conductivity (or
insulation properties) changes.
- When the road surface changes physical or conductive properties also
change.
- Wet weather mixes wth the road dirt and produces are better conductive
path and thus less of a voltage to discharge.

Does applying the brakes (better conductivity hub/disc to axle/car)
change or reduce the noise? (It will also distort the tyre shape in a
like mannner to cornering so this test may be invalidated. Try just
making the pads bind slightly with the drum/disc so it doesnt affect
tyre shape)

Does driving on a noisy stretch with a wheel on the lane marking paint
yield slightly less noise? (Wow, a new way to measure road speed!) If
this gets to be a positive test you can try one side or the other to see
if it is wheel dependent. (The kerb side tyres will of course have
slightly more surface on the road due to road camber,)

Hard to test but does the noise stop straight away on wet pavement or
does the water have to take some time to get well ingrained onto the
tread and side surfaces of the tyre?

The more tyre surface that is on the road (eg smooth pavement, cornering
G or wet pavement) the more likely the static charge will discharge at a
lower voltage (ie less noisy) Can you make the problem worse by adding
some more air to your tyres?

Road material conductivity to the underlying "ground" I dont think would
be that significant but I'll admit I have never measured it. I would
have thought that it is low enough resistance (including any rebar!) to
not be factored in. I am prepared to be shot down over this though!

Interesting/Intriguing situation! You can of course just try some of
that conductive powder that goes inside the tyre. Something like that
green roadside puncture repair stuff may also help and additionally give
you some protection for its priamry use!

Please get back to us with what you find.

Cheers Bob VK2YQA/W5 East Texas

(It is too dangerous for me to use AR in the car nowadays. I am so use
to veering the "wrong way" from driving for so long on the other side I
cant afford the risk! Sigh! - Yeah I also spell "tyre" the other way!)

Mark wrote:
WHEEL STATIC ONLY ON SOME PATCHES OF PAVEMENT? WHY?