I know what your saying Mick.
The Fj 12 suffered the same, and for a matter of fact so does the B6.
And to answer your question the shinko fronts 009 and 005 do not have a center rib, or groove for the want of a better word.
I have only used the 005 on the front.
However I dont mind the 009 on the rear of the B6, in fact the 009 rear i'm removing from the B6 soon is the one I was bedding in when we meet up for a blast on gods road. The reason I've gone the 005 on the rear of the Rex is, customer feed back on bikes up and beyond 130 rear wheel Horse power, and bucket loads of grunt, have noted if the 009 is not as grippy and so it should be, being a harder compound, and when tested will cut loose under extreme riding, like who here would do that
. But having said that, you have seen for yourself the B6 in action, and the drive I was getting out of corners, mind you it is 30 hp short.