Hey rruff, i think you are conflating what josh said about the attack and the 4000s a little. Obviously squared off tires aren't aero but what josh said was that an attack after 300km was as bad in terms of aero as a 25mm 4000s; but that after 500km a 23mm 4000s only adds about 10-15g of drag.

His statement was that the 4000s keeps its aerodynamics better than other tires. I think that either way, I wouldn't sweat tire wear on a rear tire in terms of aerodynamics.

Here's Josh's comment http://forum.slowtwitch.com/...um.cgi?post=4344867;