Different tyres/tires on A3 Quattro

I've just picked up an X-reg A3 1.8T Quattro from a dealer. Looking through the manual it says
"On vehicles with 4wd all 4 wheels must always be fitted with tyres
of the same type, make, and tread pattern, so that the drive system is not damaged as a result of constant differences in the wheel speeds"
Mine's got (newish) Pirelli P6000 tyres on both front and one rear wheel, with a (more worn) Michelin Primacy on the other rear wheel. (All 205/55 R 16 91W)
Is this a problem?
Thanks for any advice, Reg
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snipped-for-privacy@hotmail.co.uk wrote:

IMO, I think you've answered your own question. The manual is quite specific in this regard as you've found. Although my current car is not a Quattro, I recall a 4wd that I did have before and having to change all four tyres at once to prevent any damage. I believe this is still the case (although I could be wrong).
Best get it checked professionally and replaced as necessary.
Have you checked the spare? Is it a P6000 also?
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The A3 is fitted with the Haldex 4WD system. AFAIK, this system is more resilient to differing tyres than the Torsen system of larger Audis. It would still be better to have all tyres of the same manufacturer and type.
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I have the Torsen system on my A4, and have been told that as long as the tires on the same axle are the same and have similar tread wear (i.e., within about 3%), you're okay. That said, isn't the Haldex system a part-time system? That is, the car is FWD until slippage is sensed and the Haldex sends power to the rear wheels? Versus my A4, which is full-time AWD... The only reason I mention this is that if the mis-matched tires are on the rear, it would not be as big an issue with your car (with part-time AWD) than on mine (with full-time AWD).
Dan D '04 A4 1.8Tq MT-6 Central NJ USA
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Uytkownik "Dano58" wrote

According to the little snipped posted on Tire Rack which they say they took from the owner's manual: ""rolling radius of all 4 tires must remain the same or within 4/32-inch of each other in remaining tread depth": http://www.tirerack.com/tires/tiretech/techpage.jsp?techid 

True, but it can be argued that different rotational speeds between wheels (caused by different tread depth) can be decoded by the system as slippage thus causing the system to engage. But as noted, it's not as crucial on Haldex as it is on torsen. And honestly, I think things like tire pressure and carrying load (full trunk vs. empty) may cause higher variations in rotational speeds than differences in tread depth. I may be wrong though...
Cheers,
Pete
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Pete wrote:

Thanks for your good advice everybody. As ever, the official line (as per the manual) will always err on the side of caution, so maybe it's not completely black-and-white. That said, the dealer has now agreed to replace the different tyre with one the same as the rest so I'm happy. Next issue, I guess, is how different the tread depth will be.......... Thanks, Reg
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good news! New tyres tend to have around 8mm of tread
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