Hey Alex,
A few of us tested them on our club track last April/May. Nick's comments are spot on - they worked well in 13.5 once you figure out the tire compound regime. I found, on a lower bite track, that I had to sauce the rears for 40mins while I sauced the fronts only 15mins. This kept a good balance in front/rear grip for the entire eight minutes. As the grip in the track grows, then the tires become less sensitive to this balance.
There is no question that the Blu/Greene compounds are a little better in lower grip, but it can be mitigated as I describe above, and the advantage really trails off once the grip comes up.
The other really interesting thing is that the Spec tires help groove up the track. Conversely the Blu/Greene compounds actually remove grip from the track. This was a weird concept to me at first, until Bodine explained his experience at the Worlds last year, and Frank Calandra backed it up too. At the 12th Worlds, all cars were using the Blu/Greene compounds and a black groove never developed - ever. Bodine likened the traction to a 3/10 if the Victoria WCICS race is a 6/10. Those tires just do not lay down grip, so they rely on TC rubber classes and WorldGT classes to lay down the grip.
So, I am hoping our club track will get grippier faster by us switching to the Spec tire this year.
Oh, and yes the wear on the spec tire is very good - better than Blu/Greene. The spec tire is marginally more expensive than Blu/Greene as you pointed out, but I believe that cost is offset by the slightly longer wear.
I hope that helps,
Blake
