[s-cars] Was: Subject: Re: One bad tire on my Quattro (torsen) NOW: Running tires which may not be exactly the same size due to wear

[Tom Winter]

Dave Kase <davekase at pdqlocks.com> wrote
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=18

courtesy of P. Schulz...
_____
Link leads to this:

Rotating Tires

Because the front and rear tires of all-wheel drive and four-wheel drive
vehicles perform different duties while accelerating, braking and cornering,
tire rotation is important to even out, and maintain equivalent treadwear of
all of the vehicle's tires to minimize potential driveline stresses.

If the vehicle is equipped with a matching road wheel and full-sized spare
tire, they should be integrated into the vehicle's rotation pattern at the
first tire rotation. This will allow all five of the vehicle's tires to
share in the workload and wear at similar rates. In the event that a single
tire is damaged and has to be removed from service, this will allow the
tread depth equivalent spare tire to be used with the remaining three tires.

If the spare is not integrated into the vehicle's tire rotation pattern, it
will not match the tread depth of the four worn tires on the ground when
called into service. Additionally, if a single tire is replaced by the full
size spare tire, hopefully the new replacement tire can remain as the spare
tire until the other four tires have worn out and need to be replaced.
____

OK, so call me stupid, but if you are rotating the 5th tire (spare) into the
mix it's highly unlikely that all of your tires will be the same size. For
example. I rotate spare into the mix for the first time, removing one used
tire. Spare is new, other tires are used = different tread depth and no
bueno according to Tire Rack. Rotate tires again, and then the "spare"
(which started out new) stays on, one "old" tire comes off, and the old
"spare" gets put on. First spare is a different size as is the second spare,
too. But both are now being used as daily drivers.

Hmmmm.....

And then throw in slightly underinflated tires (yeah I know, but I don't
check mine every day, sorry) and the different wear between front and back
or if your alignment is slightly off and you have more wear on one tire. . .

I'm guessing I'm screwed, as it's highly unlikely that all my tires are the
same. Close, yeah, but it sounds like not close enough. . .

I'd better go spend some money at Tire Rack to make it all good again ;-)

Tom '95 S6 Avant with the donut "spare" which remains in the trunk and is
not part of the normal cycle of tire rotation.