Singlespeeddad

Ok, from what I see(correct me if I am wrong) it looks like the inside of you drivers rear wheel is worn more than the outside & the pass rear is similar but not as predominant; with a larger amount of wear in the middle.

The fronts appear to be "cupped" which is a result of an imbalance &/or due to a rubber compound which is unable to sustain the vehicle capabilites. (I have seen this with specific tires on specific rigs i.e. Dunlop SP 9000 on Merc ML's)

As for the rear, If what I stated above is correct, then that would indicate a "Camber" wear. Basically try to picture a tire sitting straight up & down. That would be 0deg camber. Now if the top leans IN TOWARDS the vehicle, that would be negative Camber. Consequently, if the top leans AWAY from the vehicle that would be positive camber.
https://forums.audiworld.com/attachm...1&d=1293768846

Now...Your vehicle should have the ideal alignment at ride height #2. As you raise your allroad, the camber would have a tendency to move in a more POSITIVE direction & as you lowered it, it would move in a more NEGATIVE direction.

In either case, lowering the vehicle with a 402 would always cause more NEG camber. If it is low enough, you would not be able to make the necessary adjustments with the factory set up. Hence the Adjustable control arms available.

As a tech, my first recommendation would be to get the vehicle aligned at a shop & inform them that you would like it set at lower ride height(assuming you do most of your driving at level 1) & Also let them know if you have lowered it from factory spec.

Now for the explanation:
--CAMBER--
when a tire sits at a neg camber, more of the vehicles load is placed on a smaller portion of the tire, this causes increased pressure on said portion of the tire.(think pushing down harder on a pencil while coloring back & forth) This increases the amount of wear because there is more pressure across a smaller surface area.
--TOE--
this is basically the tires pointing at or away from each other. This "DRAGS" the tire sideways across the pavement while you drive. If it has "TOE OUT" the front edges are further apart that the back edges(as measured from the left to right on said axle) & "TOE IN" is well like pointing you toes in toward each other.
--CASTER--
This is a NON-WEARING ANGLE!!!!!!!!! Caster is best described as the front of a shopping cart the wheels always want to flip back this causes the steering wheel to straighten out after making a turn

So....when a vehicle is out of alignment, the tires wear at a rate of about +3% per every 1-deg out of spec.

Sorry about the long post, hope it helps someone.

Kristopher

Logic seems to indicate that it is an alignment issue. If not a static alignment then you'd presume a dynamic issue due to limited suspension travel at the lower heights.

Yet even with that in mind I find it quite shocking the wear is so severe over such short distance that it could be attributed to alignment issues.

Stranger things have happened!

Brandon@Baak2Basics

I have 2 degrees of negative camber on each corner as previously stated. I am completely fine with having camber wear but to have them waste away in less 5,000 miles THAT is a major problem. It shows that there are more things in play than just camber alone. EVERYTHING except the CAMBER is within audi's spec for the allroad. Alignment is not the issue. The excessive wear is being caused by something else. At least that is my thought.
I'll measure the distance between the axles as suggested and report back. Thanks guys!

Brandon@Baak2Basics

Btw not sure if I ever mentioned this. Ngp specializes in alignment for lowered cars and they told me if that at the height I drive the car (level 2) it would not be possible to have the CAMBER in spec but they could set it equal all the way around and make sure everything else is set properly to spec. I even have the spec sheet for my car. I'll post that later

badroadsinmtl

Most AR owners ride on L2. Since I have adjusted to original specs and have driven 5000 kms since, I see no change to the tire tread.

Brandon@Baak2Basics

Got ANOTHER alignment and a full set of Michelin Pilot Sport PS2's (255/35/20 all around. Also changed the rear struts. I have driven 500 miles on them and I've been tracking the tire wear. The fronts should last 17,000 miles and the rears are wearing at such a severe rate they are only going to last 4,100 miles!!!! WTF. I lost a negligible amount of tread in the front over the 500 miles but over 1mm in the rear!!! I replaced ALL of the struts, ALL of the front control arms, upgraded the tie rod ends to the meyle HD's, adjusted the ride height to be equal all the way around (before the alignment was done) I don't know what else to do. Raise the car and realign? Check the steering angle sensor? Do a 1 mile roll out measurement? put the car on a 4 wheel dyno and check the wheel speed at each corner?

Does anyone have answers as to why this occurs with these cars? I have seen reports of this on multiple forums with no answers.

My last resort is to replace all of the rear subframe/control arm bushings and get yet another alignment with the car raised to the stock 402mm setting. That would be over $2,900 worth of tires and alignments in under 5,000 miles. Not to mention all of the struts and bushings/arms that have been replaced recently. HELP!!!!

No matter how low a car is, if the wheels are aligned properly my thought is that there should be no excessive tire wear. I have seen chopped up mini trucks dragging frame get better mileage than I'm getting out of a set of tires. Could it possibly be something with the quattro? Or is it something I'm missing? Is there more to it than just a normal alignment?

Kristopher

All 4 rims are the same width?

I saw a Porsche Cayenne with the same issue. His was obvious though - he had a 40 series on the back and a 45 on the front. It did manage to strip all the tread off the rears though (counter intuitive to what I'd expected)

See my post a while back (#8) - any chance of a gearing change in the life of the car (front diff, rear diff, ?)

vwraceguy

If something jammed the rear diff spider gears to be locked, then the rear tires would scrub around every corner and wear out extremely fast.

Brandon@Baak2Basics

No Gearing changes to the vehicle.

I topped off the rear diff fluid a few thousand miles ago and everything looked good.

As previously stated the front wheels are 20x8.5 and the rears are 20x9.5.
Last set of tires I burned through on the rear were similar to the porsche you described (245/35/20 front and 255/35/20 rear)

That lead me to purchase the same size tires all the way around which I now have Michelin Pilot Sport PS2's 255/35/20.

Last alignment specs are as follows:

Front:
Camber Left -2.1 degrees
Camber Right -2.2 degrees
Toe Left 0.18 degrees
Toe Right 0.19 degrees
Total Toe Front: 0.37 degrees

Rear:
Camber Left -2.1 degrees
Camber Right -2.1 degrees
Toe Left 0.23 degrees
Toe Right 0.22 degrees
Total Toe Rear: 0.45 degrees

Kristopher

Just calculating tire sizes alone, that's a 0.1" difference in radius front-to-back. 0.125" is within the spec limit suggested by Audi (4/32 is allowable).

But now rim width also comes into play, and your front rims are an inch more narrow than the tread, where the rears are only .5" narrower.

What that would suggest is your rears will be even taller given that the sidewall is more straight. You could be over the the 0.125" spec limit with that setup.


Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
255/35-20 3.5in 13.5in 27.0in 84.9in 746 0.0%
245/35-20 3.4in 13.4in 26.8in 84.0in 754 -1.0%

Even with the same size tires, just due to rim width differences you may have a problem. You can only get away with a 4/32 variance which is 0.125" in radius. That half inch wider rim out back might be the devil.

My only suggestion is to get the same width wheels, or look at other staggered setup AWDs and see what tire sizes they run on their wheels (if you can find a 8.5x20 and 9.5x20 setups).

[edit: numbers]