I agree with Burgundymog and Milligoon, get some miles on them! A couple of my friends use them for competition and swear by them, both top runners. If you still have problems I'd suggest you contact Kumho Australia and seek their advice/opinion.
1969 4/4 1995 plus 8 1996 Plus 4 4seater 2002 Aero S1 2013 M3W 2014 Plus 8