Taylor spark plug wires

I burned through two sets of 8mm ign wires in 30,000 miles before switching to Taylor wire 11.1 mm thick with FG boots to insulate the plug from the wire. The wires have about 70,000 miles on them now and are still working fine. I switched to Thorley headers at the same time so that reduced some heat. How thick were the Taylor wires you bought? Were the 4 wires that failed on the same head? Were these the same wires that failed originally? I did what Don suggested and ran ducting to cool the plugs, unfortunately rain got into the ducting during a storm and my exhaust manifolds cracked, that's when I switched to headers and the thicker wires.