i used A539 for less then 2 yeras, drove 45000Kms
I also had a bump on the side wall after 25000 Kms, after that i used a tube in that particular tyre.
i was very happy with my purchase when i got rid of Brand new screechy Generals, but in the end i am not satidfied with these tyres. sidewalls are soft for our road conditions which give comfort but i had puctured sidewalls, a bubble, and dozen other punctures, because of extra softness of these tyres.
do get them inflated between 30-32 pounds, then results will be better.