Re: 5k bad vibrations, conclusion

[Don Hoefer <hoefer@cary.eng.pko.dec.com>]

My '82 Coupe had the same problem all of the time when I
had the OEM Firestone S660 tires.  I found that it would
go away when I drove at 70MPH for 20 minutes or so.  I also
observed that the car would develop the same vibrations at
the speed that I drove most often at (60-65MPH).  I assume
that driving on the temporary flat spots would wear the tire
out of balance over time.  My dealer said that the problem
was constant with Porches.  Owners were always coming in and
asking the dealer to balance the tires after vacations and
business trips.  Balancing them won't do any good if they are
not round.  The dealer said that they would tell the Porche
owners to drive the cars at least 100 miles and then have tires
balanced if the problem was still there.

Curiously, my Yokohama AVS U+4s don't seem to have this problem.

Don Hoefer
'82 Coupe