15% doesn't seem like much.
agreed, but it all depends on the situation. For me it means changing the tyres less often (already a big plus in itself), or managing to complete a tour without having to change a tyre on the go, as I had to do last year in Edinburgh. I was some 1000 miles from home and running on the cords. That is exactly that extra bit of mileage. I get between 5000 and 7000 miles out of my rears.
- single or dual compound for the new tyre ?
- and the tread pattern hasn't really changed at all.
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according to the guy at Pirelli, dual compound. Harder in the middle compared with the ST (hence longer life) and softer on the sides (more grip). The thread pattern changes are indeed small, but in my experience they have a big influence. When the groove gets increasingly wider towards the border of the tyre (as in the GT), it also increases slip angle, making the tire a bit more progressive and, for the less experienced rider, a bit more predictable when approaching the limit.
Slick tyres do offer more grip on the dry when leaning, but they grip, more lean, grip, more lean, gone.
Grooves also give water an escape route from under the contact patch when it's wet.
One thing I noticed while looking at the GT on the Pirelli stand, is that it seems to have a more rounded profile, not as "pointy" as the ST. I like how the C14 falls into the curve while on the ST, much nicer and easier than on the OEM Bridgestones, which made the bike rather reluctant to turn in. However, this "pointy-ness" also means that the counter force that has to be exerted on the handlebar (pushing on the grip on the inside of the curve) to hold a line on a constant radius curve is higher. Maybe the new profile addresses this (?)
