mismatched tires

[Ti Kan]

William Magliocco writes:
> the $500 Q is now resting comfortably at my home.  I
> was able to drive it 50 miles today without incident
> or any engine fault codes-4444 all the way.
> 
> However, I was told when I picked up the title
> yesterday that the tires were an issue.
> 
> OK-the front pair are 215/60 and the rear are 205/60
> all on the standard issue 15" wheels.
> 
> On an FWD car I would not have any concern, but since
> this is my first Q, I hope that the few mm difference
> won't mean something is chewed up.

Those two sizes have about a half-inch difference in diameter, and about
15 rotations difference in a mile.

You didn't mention what year your cars is.  If you have an open
differential car (pre-88) then it's mostly ok except when you lock the
center differential.  The different diameters will create tire scrub
and stress the differential, particularly on non-loose surfaces.
If you have a post-88 car with the Torsen center diff, then it's much
more important to have the same size tire all around, or you'd have
premature wear on the tires and the Torsen.

-Ti
01 S4 2.7 biturbo quattro
84 5000S 2.1 turbo
80 4000 2.0
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