[Vwdiesel] Tirewear in a unique pattern

[Shawn Wright]

On 29 Jun 2003 at 7:33, Pavneet Arora <pavneet_arora at waroc.com> wrote:

> Hello,
>
> Our car is a 1998 A3 Jetta TDI with 235 000 km on it.
>
> Recently, I thought that our front right bearing was going  (there was a
> whining/slapping sound form the front) so I took it in to our trusted shop
> who diagnosed it instead to be uneven tire wear on the insides of the two
> front tires.  Now the front tires were just swapped to the front this
> summer; last summer they were in the back.  The mechanic saw that there
> was some oil on one of the right struts in the back (all four dampers are
> Bilstein's replaced about two years ago).  Biltein, btw, thinks that this
> oil is normal....mmm.
>
> Now, I am seeing (or perceiving ;-)) the same tirewear pattern developing
> on the tires that were put on to the back.
>
> Anyone have any suggestions what it might be?  The mechanic, I am certain
> is going to insist that it is dampers and because getting replacement
> Bilsteins is going to take some time, and the expense of replacing them
> means that it could turn out to be an expensive experiment it they aren't
> the problem, I am looking for help.
>
> The unevenness of the wear pattern is most apparent if you run your hand
> over the inside of the wheel.  There is a "bumpiness to the feel" while on
> the outside of the tire the surface is smooth.  True to form the tires are
> nearly new :-( (Nokia NRT-2).

This is known as cupping, and is fairly common. I'm not certain what
causes it, think it is a combination of incorrect wheel alignment, tire
pressures, and/or insufficient tire rotation. My Dad ruined a set of Z rated
BFG TAs on his Jetta GTX from this - it starts on the rear, and by the time
they were rotated, the rears had cupped badly, causing noise and vibration
at hwy speeds. The tire shop said the only fix was to have the tires shaved
on a machine, and I don't recall whether the alignment was found to be off
or not. I have a set of Michelin MXV4s that came off this same car, and
they exhibited some of the same problem, although not as bad.

Have the alignment checked on a 4 wheel rack (the rears ae adjustable
with shims) if you haven't done so already. How long did they go before
rotating? Rather than fixed rotation schedules, it may be better to use 10%
of estimated tire life, since this can vary so much.

--
Shawn Wright
http://Zuiko.sls.bc.ca/swright
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