I've had three sets of the Roadtec Z6 without any problems that I can attribute to the tyre exactly. On one rear tyre I did have a blow out. But it is quite possible that it was caused by some road working activity leaving something to damage a tyre which had just gone through. It just happened to be me.
As there was some doubt to this, the tyre had the usual centre tread wear pattern for long straights and few corners. Took the bike by trailer to the local bike/tyre dealer and was told that I could not make a claim as it appeared that my tyre showed signs of being under-inflated. Not sure how a bike tyre with most wear on the centre tread would be underinflated.
Guess the supplier didn't want to honour a warranty claim.
In June 2011 I went back to try the Bridgestones newer BT23 with it's claimed 30 percent extra tread life.......Not true....