Timfoilhat

I've got 10k miles on a B9 Quattro. If I replace just one tire is that going to be a problem? Stupid staple in edge of tread/sidewall.
Does the BO use air pressure sensors, or does it count revolutions via ABS or similar?
Anything else to consider?

SDakota

The B9 uses an indirect TPMS system, so that could be a problem if one tire is slightly larger than the others. More importantly, having one tire larger than the other three will put constant stress on the AWD system - probably heat it up if nothing else. If I were you, I would call around to see if any of your tire shops has a shaving machine. If you find one that does, you can ask them if shaving down the new tire tread to match the diameter of the others would be a good idea. It should also be an identical tire - same manufacturer, same tread pattern.

Timfoilhat

I've ordered one new tire that's exact match. I'm thinking the variance between a new tire and a 10k used tire is like 1-2mm which would be within a slight variance that could happen due to pressure imbalance that seems like a normal occurance just due to temperature. If the system needed a perfect balance it would make sense that they would then install a direct tpms system thst reports exact pressure at each tire.
still interested in opinions, or facts if there's any Audi techs here.

up-n-coming

Like SDakota said, it's the quattro system you really need to worry about. Only a certain amount of difference in tire diameters is permissible. You need to get at tire gauge and measure the difference between the new tire and the old one's. Then call the dealer and find what the max difference is. If need be you can get the new tread shaved to be within spec. The down side to running tires with too much diameter difference is premature wear or failure of the quattro system.

niray99

According to Audi service the difference should be less than 3/32. I talked to service at 5-6 Audi dealers on the phone and got the same answer from all.

Timfoilhat

And this 3/32" is important only on the same axle or front to back as well?

I've requested the shop bring in a second tire so it will balance perfectly across the axle

niray99

updating my response above(because I can't edit it now)
less than OR EQUAL TO 3/32.

up-n-coming

This sounds like an odd way of going about this fix. Now your setting yourself up to be replacing tires in pairs instead of all four tires at once in the future. Go to auto zone and buy a tire tread gauge for a $1.99. Measure how much average tread you have left on the other three. Order a replacement tire from tire rack and request they shave it to the depth you need for a nominal fee.. They will ship the tire to the shop you request. By Monday or Tuesday your car will be back to perfect.

Timfoilhat

I'm concerned about shaving the tire as recommend. Sounds like a good way to lose the best part of the tread.
I'm just looking to get it right. If that means replacement of all four I'll do that.
I'm pretty sure the front wears faster than the rear. I think two new tires up front and the 10k tires at the rear (assuming the quattro doesn't object to the slight difference in overall diameter) will work out. The new fronts should wear more quickly and at some point catch up to the rear. A year past that and I'll be ready for another full set of four.

up-n-coming

Why buy two tires when you only need one and in the process discard a perfectly good undamaged tire..Like you, I'll spend if I have to but as a rule I look for the most efficient way to go about fixing a problem without leaving unnecessary money on the table. If you feel your way is the best, Good luck.