Tire Question w/ Quattro...
Assuming you did not ever rotate your tires, and did not race or have any track days, which tires would wear out first - the fronts or the rears?
I do have a reason for asking this, I got a killer deal on 2 pair of Michelin Pilots, but one pair has 60% tread left and the other pair has 80% tread left. Do I put the 80% tires on the front ot the rear? If the front's wear more quickly (which would be my guess) then the 80% go on the front, the 60% go on the rear.
As you suggested, stick the 80% tires on the front, Still rotate the tires, though, and perhaps use shorter mileage intervals when the "worn" tires are on the front.
You can get quite good tire life with regular rotation on a properly aligned A8/S8. I had a set of Bridgestone S-03's last 30k miles, including 2000 miles on track, with rotation at 3000 mile intervals.
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However, I believe it was CAR or EVO (car magazines) who conducted extensive tests with a good pair of tires in front or in the back (and a worn out pair on the opposite axle). They tested in dry and wet, both FWD and RWD cars (don't recall AWD). The key finding was that when pavement friction coeff was low (incl. wet/rain conditions), cars with the worn out pair in the rear would CONSISTENTLY (with sufficient speed or road conditions) oversteer around curves or road bents!
In one case, even the experienced prof. driver 'overshot' the curve, couldn't "collect" the car, and lost it in the ditch.
When the worn tires were mounted upfront, oversteer was more easily handled and didn't lead to scary moments.
Their main conclusion/suggestion, thus, was: unless you're an ace driver, and fully cognizant of your car's (and your own) limitations, your risk of losing control of the car in adverse conditions is much higher when the worn tires are in the back, regardless of FWD or RWD drive.
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- In the dry, I would expect oversteer to increase.
- In the wet (or snow/ice), I would expect understeer to increase.
and you're right, the latter does increase the margin of safety for any driver under the generally more hazardous low traction conditions.
The other result, though, is that the already worn front tires wear faster than the rears, and you'd never be able to rotate tires with this rule. By putting the worn tires in the rear, I was trying to get back to four uniformly worn tires.



