SCarGo02

To give it the "RWD" SUV bias?

nothing

So if you want your tires to wear evenly, put the best ones on the front and rotate occasionally.

4Driver4

understeer, the front is the best place for the best tires.

sadik007

Wow... Great response...

I am driving this car in Bosnia, and roads are bad, very bad, with a lot of snow and hills. Many times I am only car that can move at all.

So what is default differntial setting, is it 50:50.. And What is use of that button on the midle councle for locking diff. I have all 4 GoodYear M+S UltraGrip GW3, winter tires. Still cant decide where to put better tires.

Cq20V

All quattros are full-time all-wheel-drive. The transmission and
differentials will try to send power to all four wheels the time. Until
recently, cars with manual transmissions ran 50% of power to the front and
50% to the rear until something slips. I think automatics might be
different, but I don't know much about them. More recent cars like the RS4
and Q7 are using a 40/60 front-rear split to give a more rear-drive feel.

The differentials allow the wheels to travel different speeds, for instance
in a turn. Unless you have a limited slip-differential of some kind
(viscous, TorSen, etc.), the differential is "open" the power will go to the
wheel that is easiest to turn. Locking the differential "closes" it,
forcing both sides of it to rotate with the same speed. So the differential
locks do not "engage" the all-wheel-drive, they "manage" it when traction is
so low that all four wheels can't apply power to the road.

[On the B4, the center differential is a Torsen, so it automatically manages the torque front-to-rear, without driver input. The "Diff" button on the console locks the rear differential.]

Thus, say you park with your right tires on ice and your left tires on
asphalt. When you hit the gas, the right tires on ice will spin and the
lefts will not move, so you won't be able to go anywhere. However, if you
lock the rear differential, you force both rear axles to turn at the same
speed, so you'll get power to both right and left wheels in the back, and
you'll be able to move off the ice. You can imagine a similar scenario for
front/rear instead of right/left. In that case you'd want to lock the
center differential. [Not an option on B4, it does the work for you.]

Differential locks should only be used in situations like that, when you are
stuck, or on a racetrack when you want to alter handling characteristics.
In all other situations, leaving the differentials locked will ruin your
tires because in curves they will be forced to slip and wear away since they
can't turn at different rates like they'd like to. This will also channel
unnecessary torque into the differentials and wear them out faster.
Finally, if you aren't ready for it, you might lose control in a fast corner
with your differentials locked. This is why the 2nd-generation quattro
differential locks automatically disengage above about 15 mph.

You should replace all 4 tires at the same time, with 4 identical tires. If
you mix brands, ages, models, size, etc, you will end up with tires of
different circumference. This will make the tires rotate at different
speeds all the time, forcing your differentials to work all the time, for
instance when you're doing 80 on the highway, even in a straight line, and
will wear them out faster.

Also, unrelated to quattro, it's just good practice to replace all 4 at
once, since that keeps the handling characteristics of each axle balanced.
This is not important for everyday driving, but in an emergency you don't
want one axle to have a significant traction advantage or disadvantage.
This also implies that you should rotate your tires front-to-rear
periodically if they wear unevenly (most Audis wear the front tires faster).
Keeping the tires equal everywhere keeps the car nicely balanced.

If circumstances force you to only buy 2 tires, though, put them on the
rear. That will make the car understeer at the limit, which is safer for
street driving. If you put new tires on the front and have junk on the
rear, the car may tend to oversteer (or at least understeer less), which
could be harder to control in an emergency. Of course, having your worst
tires on the front hurts braking, so it's a trade-off. I guess you have to
gamble on whether you're going to need to steer to avoid a wreck
(preferable) or brake to avoid a wreck (last resort).

In short, buy tires 4 at a time and leave the differentials unlocked unless
you're in trouble!

nothing

Do you rotate your tires at all?

Cq20V

I have 3 sets of tires (summer, winter, racing), so I change very often. Each time I change tires, I rotate to keep the wear equal front-to-rear. I do not change the direction the tire rotates, e.g. rotate side-to-side.

In doing so, I keep the wear virtually identical on all four tires. So to answer your question, yes, I am unconcerned about wear, I wear my tires equally.

With that said, I don't see that much difference in wear front-to-rear on my quattro. I agree with you that the fronts wear faster, but in my experience it's not a huge difference. This is my first quattro, though, only owned for 3.5 years. I have seen the same behavior on BMWs. My old VW wore the fronts like crazy, had to rotate very often.

So my response is not applicable to the way I operate. But the question was posed "what do you do if you have 2 good tires and 2 bad tires", so I gave the answer for how to most safely play that hand if dealt it.

If it were me and I were in that position, I'd see it as an excuse to buy 4 new tires and start anew, to get the best handling and abuse my differentials the minimum amount. The point of every job is to buy a new tool, right?