One problem related to tire bubble has been reported for the 1999 Audi Quattro. The most recently reported issues are listed below.
Identified bubble in outer sidewall, beginning at tread to mid-sidewall; separation on right front tire's outer surface of Audi a6q. Goodyear dealer confirmed sidewall separation and need to replace immediately or risk catastrophic blow-out. Dealer blamed soft sidewalls as being "pot hole susceptible". But no damage to inside of tire surface! have read many other reports on this tire size reporting bubbles or catastrophic failures. (dot number: m60fbedr34 tiresize: 205/55r16).