[s-cars] One Flat Turns to Four

[Peter Golledge]

Brian,

Never understood the "oh the tires must match, danger danger Will 
Robinson" paranoia running around Audi (and Subie) land.  Consider what 
happens to the trans/diffs when you are on track or auto-x, tires are 
constantly spinning a different speeds with high loads.  The 5.7l SBC in 
the LT-1Q get one or more wheels spinning and throwing off rubber in 
tight turns, been doing this for 8 years with the same gearbox/diff 
(both stock Audi 5000TQ).

Now some math, the diff in radius according to your  measurements is 
4/32, that makes a difference in circumference of ~ 0.4" out of a total 
of 78".  So one extra rotation of the diff every 195 rotations (1200ft), 
folk worry about that, really?

Next winter come out to Colorado and spend a couple of days with our 
Gruppe-Q (http://www.gruppe-q.com/) crazies.  There you can wear down 
those tires on an ice track and give the differentials a real workout 
with some 40 deg slew, lock to lock, full throttle driving. :-)

Cheers

On 4/30/2012 8:38 PM, Brian Pleet wrote:
> I blew a tire on my 95.5 S6 traveling between Calgary and Vancouver last
> week. I heard a clunk, my aftermarket tire pressure monitoring system
> started beeping and I watched the pressure drop. Unfortunately, that
> stretch of the Trans Canada highway is the worst across the country with
> hanging wire nets to catch the rocks tumbling off the mountain. I chose to
> drive on, aware of the price of a ruined tire. Five km later I stopped in a
> safe place and changes the Blizzak winter tire with one the summer wheels I
> was transporting.
>
> First I'm told you have to replace tires in pairs, to minimize imbalance
> side to side. I ordered two replacements. Now I'm told that you have to
> replace the entire set, one for four because the quattro system would be
> upset by different tire radius. The blown tire was 7/32 tread depth, the
> other side was 7/32 and the two remaining are 8/32 left out of a starting
> depth of 11/32.
>
> Two or four? Suggestions?
>
>