Hello Mark,
I used to drive a semi trailer years back, and had the same problem. It
occurred only in fine hot weather, and the static build up used to wipe out
80m mobiling, plus the Am receiver on the broadcast band. It was what I call
"Tyre Static"

I noticed that in wet or damp weather it didn't occur, so I cured the
problem by simply introducing some graphite powder into the grease of the
outer wheel bearing on the front axle.

Later on I found that a molybdenum based greases did the same job, without
the mess of handling the graphite powder.

I also found that steel belted radials were the culprit, but the early rayon
biased tyres didn't suffer from the static build up problem at all. Main
problem was that the rayon biased tyres didn't have the speed or load
ratings the steel belted tyres have.

A big problem is that nowadays with the introduction of sealed wheel
bearings and front wheel drive vehicles makes it nigh impossible to
introduce graphite powder or to re-grease the wheel bearings.

By experimentation I found another cure, that was to put some graphite
powder inside of the tyre before mounting the tyre on the rim (wheel), that
reduces it as well. One can let the air out of the tyre and introduce
graphite powder through the valve stem and then re-inflate the tyre.

I found that the graphite powder inside of the tyre did not affect the at
all, we used to recap our truck tyres up to 3 times, only thing was the tyre
fitters hated dealing with the graphite inside of the tyre.

On another problem not really related to highway use is that when farm
tractors were fitted with UHF CB, ploughing in a paddock, static noise used
to build up to a point where communication were impossible even over a short
distance. The cure was to wipe the antenna down with a dry cloth.

Hope this helps
HarryH


"Mark" wrote in message
...
WHEEL STATIC ONLY ON SOME PATCHES OF PAVEMENT? WHY?
With the financial mess, I have started to listen to AM radio in the
car on the way to and from work for the past few weeks and I've
noticed some random static at certain locations. At first I
attributed this to some power line noise. Bit it didn't really sound
like 60 Hz buzz hash, it was more random popcorn like but I know power
lines can blow around in the wind and have strange discharges so I
didn't think too much of it for a while. But after a few days I
noticed that the static is there only when the car is moving. OK, so
its wheel static. Static electricity from the wheels or brakes or
something. OK that's not unusual either. But it is the combination
that has me curious. This static only occurs when the car is moving
and it only occurs at certain repeatable locations on my drive.
Everyday when I turn the corner from X to Y, I get the static as the
car is moving, but not when stopped at the same corner. And I never
get the static when turning the corner from A to B. If it was power
line, stopping the car wouldn't stop the static. If it is wheel
static, why does it not happen all the time and happen only at certain
locations. It seems as if these certain locations have something
special about the pavement or the water content of the soil or
something. None of that seems likely to me though, I see nothing
changing in the pavement as I drive from an area of static to an area
of non-static. It is not related to stepping on the brake or gas or
shifting gears or going over bumps or any other aspect of the car that
I can tell other than it's speed down the road.
As an experiment, I attached a drag wire under the car. The wire
drags on the ground to discharge any static build up the car. This
made no difference. Another clue, we've had no rain here in a
while. The static all stops during wet weather. Also I am in the
Philadelphia area and the AM station is in the New York area so it is
on the weak side.
I've been a ham for over 30 years and I have a lot of experience with
EMI, but this one has me scratching my head. The wheel static
changes repeatably in different locations for no apparent reason.
It's got to be something to do with the pavement. Anybody have any
experience with this?

Mark