unequivalent wheel weight & traction

[Kneale Brownson]

Audi's Type 44 universal donut spare (5k, 100, 200, V8) is a 17" wheel, but
the aspect ratio of the skinny tire is such that it matches the OEM OD (of
15" wheels with "60" ratio).   You definitely don't want to run different
OD wheels on a quattro system.  Every model manual says not to do this
because of unacceptable stresses it would place on the drive system.

At 02:20 PM 12/6/2005 -0800, Chuck Pierce wrote:
>I would think the biggest concern would the rolling diameter. If I 
>understand the Q system correctly.
>The believe the quattro system demands tires of equal diameter so as not 
>to burn up the center diff.
>The strange wheels are bound to cause the car to handle in a strange 
>manner, but the biggest concern is the diameter of the tires.
>I drove home (45mi) once on a space saver spare. Kept it to 50 mph or 
>so( damn that was hard, I have not been passed so much since I had a VW 
>transporter)
>No problems with the drive train. I checked out the dia. of the spare 
>and it was pretty close to the 16" tires I run.
>
>Chuck Pierce
>91 200tq Avant
>Schaible, David wrote:
>
>>Does anyone have any experience, or wild theory, on running different
>>wheels and tires,  such as is there any damage done by running a donut
>>spare for extended periods or running a steel wheel on one location and
>>the bbss' on the others?????  What is better, a donut spare, or a full
>>size spare of 25% more mass but similar traction?
>>
>> 
>>
>>My experience to date makes me think you could drive around on
>>practically anything like a rim with no tire on the rear and only effect
>>is reduced handling ability, which is magnified at high speed.