Tires: Tire cupping, audi a6 quattro, 2005 audi a6

Question
I have a 2005 Audi A6 Quattro with 60K miles on it.  It came originally with Michelin Pilot 245/40 R18 tires that I got 41K miles on, very nice tire, quiet and had decent grip. I replaced those tires two years ago at 41,000 with the same size Coninental ContiProContacts. Aligment was completed at the time of purchase. The tires were rotated at 10K and wear looked even. At 15,000 miles on those tires they started to rumble like knobby off-roads. I took the car back to the dealer and they said the tires were cupped on both the inside and outside edges. I checked that myself and that was true on all four tires. The outer edge grooves were all "ridged" .  I check the air pressure once per month and they have always been in range. 36 PSI in front and 33 PSI in the back. I had the care re-aligned but everything looked to be in spec. I don't get it. I now have 19,000 miles on the tires and they are making me nuts to drive with the whine and rumble.

One other curious thing.  I just bought a 2011 A6 quattro and the original equipment tires are the Continental Conti ProContacts.  The difference is the inflation recommendation on these tires is 42 PSI and the car is virtually the same. Is it possible that the replacements on my 2005 A6 have been running underinflated for 19K miles causing the problem?

Help!  

Answer
Dave,

It certainly sounds like they changed the inflation pressure recopmmendation - and perhaps as a result of other's experience.

I'd certainly recommend trying the higher pressure.  Just be aware that you will not be able to undo the wear that is already there,  but at least you will be able to slow it down.