@Fox - in my experience, there is very little difference between 'TT' tyres and road tyres. The main diff is puncture protection and the reduced rolling resistance it brings.
Millar reckons there's quite a big difference in the wet (generally). He was also talking about tyre pressure too though, he reckoned a lot had their tyres pumped up too hard. He had quite a bee in his bonnet about it :)
@Fox - in my experience, there is very little difference between 'TT' tyres and road tyres. The main diff is puncture protection and the reduced rolling resistance it brings.