I bought my 2005 Roadster Jan 1 2011 and it had 42,000 miles on the OEM Continentals.
I replaced them at 45,000 with Hankooks and they are currently at around 1/2 gone at 61,000 miles.
( I have a new set of Hankooks bought on sale stacked in the garage )
+++ as to the questions above on "the top not working" - need more input.